i'll chime in here, too. the 12-27 will definitely help. so will a compact crank.

i did a bunch of hillwork in a 11-23 over the weekend, and it was pure hell. i loved it, don't get me wrong, but it was hell.

on a 12-27, some of those hills would have been cake, or at least i hope they would have.

55/rad had a compact crank, and he flew up those hills. mind you, he's better at that stuff than i am, but he had the cadence rollin, while i was just grinding. i'm beginning to see the logic in that.

i really like pushing 53x11 on the flats, but i think i'm going to put on my 12-27 for longer, steeper rides. my chain is too short to do both, so i have 2 chains... one for the 11-23 and another for the 12-27.

so, yeah -- it does make a difference.