On the bands vs. bolts question, the bands will save you some repair time if a tree jumps out in front of you or you cartwheel a landing. Recommended on trainers exactly for that reason.

On the Evolution engines, I have a .46 and it ran horribly at first. I took it apart and figured out that the rear bearing wasn't pressed on the crank far enough, creating an air leak. Fixed that, and now I am truly amazed at how well it runs!