I'm not sure what speeds we've seen on a powder climb. I do remember at one point seeing around 38 to 40 on mine, but never really paid any attention cuz I was too busy enjoying the climb.
I do know that between mine, my brothers and my dad's zx, who has a 156x15, that going across a lake blazing our own trail, we can keep up with a 08 XP 800 154. When we did that, all 4 sleds saw speeds of 58 to 60 in the powder, but none of us have climb speeds, sorry.
What's interesting and makes my buddy with the XP want to almost cry is that after he gets the hole shot and gets to 60 quicker than us 3, that on a race across a lake blazing trail in about a foot of powder that I can catch up to him. Keep in mind that on our last trip in Jan this year when we did that race I was having engine problems the entire week (couldn't pull rpm's), and after the trip found out that my raves were junk, my pistons were about to go, and the nikosil was peeling away.
What was interesting was even though I was having engine problems, I was able to slowly pull away on my brother and my dad. Judging on that info, it's hard to say which track is best. We are doing a trip in 2 weeks, and I have a fresh rebuild, so I'll get you some more info when we get back.
Other info: My brothers 02 and my 01 are geared at 18/45. My dads 01 is at 17/47. All three have 9 tooth drivers. All 3 have Paragon secondarys. The only difference between mine and theirs besides gearing is the fabcraft tunnel giving me lots of paddle clearance.