I built a Surly LM with a Larry this past Fall and was riding it with 165 KH Moments, which worked okay, but I found that it was significantly harder to climb and descend in comparison to the same uni with a Duro 26 x 3. Since the diameter of the Larry is so close to a big 29er, but so much heavier and wide bodied, I figured what I really needed was a longer crank. That was where my search began…
First up, the QuAx cast aluminum ISIS cranks, these are what comes standard on non-muni QuAx unis and what used to come on Nimbus before they created the Ventures. After talking to Josh at UDC, I scrored a couple pairs and took them riding. He assured me that they were actually pretty strong and would take a decent beating as long as I didn’t do big drops; we’re safe there, I ain’t much for big drops.
Well, they worked as expected, a true 170mm crank, went on easy, one side did seem to have a bigger ISIS tolerance, but worked out fine. The Q factor is bigger than the 165 Moments, but this turned out to be a good thing as it gave me more lateral control. These are a very light crank, probably 1/3 lighter than Moments. All in all, a great crank for not much money ($10)!
Second up, the QuAx Chromoly steel cranks. These are not easy to find, it took a bunch of searching until I found them in stock at Giroux’s in Canada. $100 USD and a week later, they appeared, black, shiney, and oh so light! This is my second pair, had some on my first 26 muni and sold them (dumb move). In contrast to 165 Moments, these are lighter and have nearly the same Q factor, so less Q than the aluminum 170 QuAx cranks.
The chromoly QuAx cranks are pretty nice, work well for a big wheel, not quite as much control as the QuAx aluminum cranks, but they are much stronger and I have better pedal clearance, and of they look so nice with my black Surly frame 
All in all, I was really suprised that adding just 5mm was such a huge improvement in my power for climbing and decending. The added length is so good that I will probably ditch my 165 Moments on my KH FR 29er and put on the QuAx 170 aluminum cranks
BTW, the aluminum QuAx 170’s are on sale at UDC USA for just $10 a pair, not bad for ISIS standard cranks