I use 172.5 cranks with egg-beater pedals. It's not really that unusual of a setup.
From what I understand, 5mm is a pretty pronounced difference in terms of BB height. Would it matter more to a pro, sure, but in the end, he's going to ride what he's given. I have to pay for the damned thing, so I'm trying to make an informed decision. No hand-wringing here, just trying to educate myself.
I guess that dry weather hints at fast courses which would give the advantage to the Crux. I don't think I remember many fast corners through the season. Maybe a couple at SpookyCross, I guess. It seems that most of our courses are pretty zig-zaggy with pretty tight corners. If you can start pedaling a 1/2 second before the next guy, then that's got to be an advantage.