Yes, but we all ignore it… 
Talk to Scott, He’ll probably let you try out his geared 26 before he takes the wheel apart.
I would go 26" Schlumpf as that’s what I have. As the MN trails aren’t that technical you should be able to ride a good chunk of them in high gear. If you had a 29" Schlumpf, as you don’t really have trail heads to ride to, I don’t think you’d be able to use the gear very much unless you are planning on riding flat dirt roads. Plus it’s smaller and easier to travel with in cars, planes, etc.
I’m with Munisano, I have some big multi day plans that involve a variety of surfaces and long distances, so I can either plug along on a 29er (slow) or take the 36er and walk some hills.
Face it, small wheels are slow, that’s why people ride 36ers and Gunis.
The 36er not only gobbles terrain, but i’s extremely stable, so great for cruising, but it can be a handful on tech terrain and when ridden for long distances on tech terrain it is more tiring than a smaller wheel. I rode our local single track area last night on the 36er and I got worked way more than if I had taken a 29er, but dang was it fast and fun; when I wasn’t drowning in my own sweat!
It’s frustrating that we only have one gear ration to choose from 
If we had gear choices, then choosing a 29 guni 1:1.25 would be a natural choice for muni and a 36 guni 1:0.75 would be a natural choice for XC touring.
Once the Surly Knard 29 x 3 is ready, I’m going to run it on my Oregon, then I am thinking about making my KH 29 into a guni.
So munisano, what multiday trip are you looking at? Pinhoti? My thoughts are more West, like CO to UT, maybe something in MT or WY.
After sleeping on it I’ve decided that I’d recommend a geared 26er over a geared 29er much for the same reasons tholub suggested. Again it really depends on how and where you ride and what your goals are. I know since I like riding my geared KH24 so much, have ridden it all kinds of ways, distances and terrains, that a 26" version will be MOSTLY the same but slightly better because of the improved roll-over ability and slight increase in speed overall in both low and high gear. I was just concerned that the 29" in high gear may be a bit too much gearing to be of much use where I ride. I can ride my KH24 in high gear on some trails and a lot of roads around where I live and just think the high gear in the 29" would be a bit too tall. In addition it will be nice to have more tire choices in the 26er versus my 24. The 26er will be far more responsive than the 29er (or 36er, sorry Nurse Ben) and lighter and easier to travel with. So when I decide to upgrade my MUni this Winter after over 5 years of using my KH24 it will be to a KH26. I think a lot of my decision comes down to my back ground and experience. I’ve never been much of a cyclist but a long time runner so the thought of trying to go fast as possible on the trails; approaching cycling speeds never crossed my mind and in truth isn’t very important. To me if I can ride, on average, faster than I can hike or sometimes even run; especially over long distances then I’m satisfied; I have no desire to be mountain bike fast.
So that’s my thoughts and what my gut says to do. Not sure if it’s of any help but there it goes.
@NurseBen: I may do a training ride on the Georgia Pinhoti next Spring but my real goal multi-day epic (actually multi-week) is out West as well next Summer. Can’t wait!
I’m doing this same exercise and keep going back and forth. Here are the points I’m considering in addition to the pros/cons listed by others:
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I’m pretty sure all my high gear riding would be on paved roads that get me to and between trails. I think either option would be fine for this but the 29" might have a slight advantage.
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For really steep trail climbs the 26" seems to have an advantage but lately I surprise myself on climbs every time I go out on the 29".
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I like having the 26" as a bash-about muni for playing around and would be disinclined to treat it this way with an expensive hub in the wheel.
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Unlike Ben, I don’t feel an ungeared 26" with 150mm cranks is too slow on trails. But I do agree with him about the 29" rolling obstacles more easily.
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My 36" with 137mm cranks is great on fire roads and smoother trails. According to Eric’s chart a geared up 26" wheel with 150s would give about the same gain ratio. Despite that, I’ve read enough Schlumpf threads to know better than to expect that the 26" in high gear will ride as easily the 36". Still, I’d like to think that some day I’d have the skill to ride these areas in high gear on the 26" but it would be tougher on the 29".
I started with a 29" guni, then pretty quickly switched it to 26". High gear on the 29 is pretty good on the road, but not as good as ungeared 36. Off road, high gear on the 29 is generally too high, IMO. I think the 26 is a better size for a guni overall, and I was able to use high gear quite a bit for xc trails. The one situation that a 29 guni might be better is for touring with air travel; but not for muni.
All that said, in the end I sold my hub and am now focusing on ungeared 29 and 36 riding. I used to live in MN, and personally I’d go with ungeared 36 for most of those trails over either geared size. I’d fear accusations of becoming a Disciple Of Ben, but I note that I sold my hub before he did. 
I think all unis should be considered bash-about unis. If you’re not going to push yourself and be willing to let the thing drop and bounce when you fall, then what’s the point? Yeah, it’s a lot of money in the hub, but really it should be able to take it.
I don’t think the Schlumpf really has problems with being beat up; I bought my 29er in 2008 (shortly after Ride the Lobster) and have used it extensively on some pretty serious MUni rides, including at least two California MUni Weekends where almost everyone else was on ungeared 24/26. The failures seem to be material and manufacturing related; I haven’t seen anyone break a Schlumpf by doing a drop or hitting it on a rock or anything like that. (And I’ve seen a lot of people with broken Schlumpfs).
I’m also planning to get a Schlumpf hub, probably sometime the next year. Are there any news on when the next generation of hubs mentioned in this thread will be available?
It’s a bit early to decide, but I guess I will go with a 26er. For me it’s not so important going faster on streets or dirt roads (with a 29er) but to be able to ride more of the easier single trails in high gear (more likely with a 26er). Additionally, I really love riding my 24x3 muni and would really like to be able to ride the same uphills and technical downhills with my future guni.
What I want to hear about is a smaller step up (25-30%) and a step down.
If I had a step down on my 36er, for long/steep climbing and steep/tight tech descents, there would be no reason to get a smaller wheeled guni.
2.5 extra pounds of rotating weight are a great reason to get a smaller wheeled guni. If we had reasonable gearing no one would ever ride a 36".
That’s only because you don’t spend enough time riding a 36er off road 
I have no need for anything smaller than a 29er unless I do trials.
Look, I ride long distances off-road with 36er riders all the time, and I can tell you with no hesitation that they are at a significant disadvantage in pretty much every off-road situation except completely smooth fire road–and there they only have an advantage if they’re also geared. A bike-sized wheel with bike-range gearing would represent the end of the 36, for the same reasons it did for bicycles.
People would still ride 36ers, just because they are fun.
It could be logically argued that a more stable cycle, that’s easier to learn to ride, with a more efficient drivetrain, and the ability to carry more gear without balance issues, would put an end to the unicycle as we know it. But bicycles haven’t put unis out of existence yet.
I can vouch for Tom being a big-wheel maniac. He was mashing it offroad before Ben knew what “muni” meant.
True.
Seriously? 36ers are way too much fun to stop riding just because better gearing comes along. Now there are people discovering 36" MTBs, which is why we are getting a better 36" tire made.
Anyway, I don’t think Gilby was concerned about 36ers. Another point I thought was interesting is that I measured my “26-inch” wheel at 27.5" in diameter (the Continental Trail King 2.4 is a pretty tall tire) and my 29er at 29.25" (WTB Wolverine 2.2). So the difference is under 2" in 1:1 and ~3" when geared up.
You guys are sooo serious, can’t see the joke through the trees 
Puleeze, what’s new gets old, gear changes, people try differemt things, the world goes round. Tholub was the one who told me, belatedly, that a guni was not what I thought it would be… so I got an interesting experience and it didn’t cost me much more than three hundred dollars :o
I know the OP isn’t interested in 36ers, but what I didn’t find in a 26guni, I did find in a 36 muni…
I think you “no boys” are missing out. I love riding my 36er off road, esp on technical muni, it is amazing how well that big wheel covers ground and bridges obstacles. Yesterday I went out to the local single track and cleaned a 1/4 mile double crux hill covered in loose rock and offcamber ledges. I did it with two rests and no UPDs, quite possibly my best climb up that hill to date on any wheel. Who says a 36er ain’t for muni?!
So you doubt what I say, but then consider how a 3" tire differs from a 2" tire, the larger tire provides more support, more cushion, makes rough terrain easier to ride. Now apply that thinking to the a comparison between a 24" and a 36" wheels: bridging obstacles on a wheel that is 50% taller is like comparing how much higher you could jump if you grew from 6’ tall to 9’ tall.
But what do I know, I’m so new to unicyclin’ I can’t even spell it right, eh Maestro 
I think we need a Schlumpf with a smaller step up and we need a downgeared hub. I have the cash…
OK, fair enough, there would still be at least as large a percentage of 36" unicycle riders as there are 36" bike riders. (That is, virtually zero but not exactly zero).
I’m sure for $10K or so Florian would custom machine you something.
A smaller high gear on the Schlumpf, and a downgeared hub would both be total market losers. Really the idea of riding a 36" with a hub geared so it can be effectively 29" is absolutely insane. It would be nice to have more than two gears on the Schlumpf but the high gear is still not nearly high enough.