Speed sensor is important for distance measurement. No idea if the front or rear facing is better, though I suspect rear. Depends on the shape (try to imitate a tear drop with the thin part of the tear drop trailing). Rear brake mount is nice, but depends on the fork (Jamis does a great job with it) and most importantly the cable gong to it. With the able hanging out, it often takes away any advantage from putting the brake back there in the first place. Center pull on the front trumps either way standard, though there were a few bikes at interbike which looked interesting (one was the jamis, and another ran the cable THROUGH the steerer tube). Good luck.