I ride the Nimbus 29" road with a Marathon Supreme on the street that I am happy with. I am curious as to what difference a KH 29" would have if any for the type of riding I do. I considered a 36", but I would not be going any further on a 36" than I already ride on my 29". The extra few miles/hour on the 36" is not really that important to me. It would probably be fun to ride the 36" every once in a while, but that doesn’t justify all of the money I would spend on one.
AFAIK, the only difference would be in the rim width that is wider on the KH.
It would allow better cushion at lower pressure or better seating when mounting higher volume tyres.
But all in all, in a road use perspective, nothing too fancy. The length of the cranks you use will make more difference.
And as a side note, there is reports from a user with seating problem on road low volume tyres (like the Big Apple 29x2.0) on the very wide KH rim.
Thanks for the info. I use 125 cranks. I’m afraid that if I went to 114’s, I would have some trouble getting up some of the hills that I climb. I changed the seat to a KH, other than the cranks, I can’t think of anything else to change now. I happen to like the Apple Maraton 2.0 tire. It changed the whole dynamics of my ride. Big improvement from the Apple 2.35 that came with the uni.
Are you running the stock rim on the Nimbus 29" Road? I have the same Uni and tried running a Kenda Small Block 8 that was a 2.0 and had a rather shocking blow out. Street riding only and the blow out put a foot long hole in the sidewall of the tire. I called UDC and talked to them about it and they told me the single walled stock rim needed the wider tire. I currently have a 2.4 Maxis Ardent on it and it seems to be fine, even off road. Although, if you have a newer Uni than mine it could have a double walled rim.
Yes, I am running the stock rim. No problem using the 2.0 Marathon. I bought the uni new last December. Someone at UDC told me I can run anything from a 1.9 to a 2.4 with the rim on it. I weigh 160lbs and keep the tire pressure at around 50 psi.
For what it seems like you’re riding I think the KH is overkill and not worth the extra money. I’m getting a KH 29 this friday so I can let you know what my first impressions are. Hope that could help. 
I have to say that I really like my Nimbus 29er and other than the blowout it has been trouble free. Weather permitting, I put 25 or more miles on it in a week. Maybe it is just inexperience on my part, but I really can’t imagine how changing the frame would make it ride better. Different tires change the ride. A different seat would produce a different feel. I just can’t see the frame changing things. I’m a bit bigger than you at 225 and on the street I run about 35 psi in my tire.
i have no experience on this matter, but from what i’ve been reading on this forum, the frame may be a little bit lighter (?) and maybe stiffer.
That would eventually help when riding steep hills and/or rough terrain.
You can still buy the frame because it’s a KH and maybe because you are planning to put a disc brake on it.
Greetings
Byc