I'd definitely say that a smaller bike can help with climbing. I used to ride a bike that was too long for me and on very steep hills I would have the front wheel lift up. I'm much shorter than you, but I'm also longer in the leg and quite short in the arms and torso. What it meant was that I couldn't get my weight over the front of the bike to keep that front wheel down - now it only happened on very steep hills - we're talking up in the 20%'s here, but I also now have much, much more power now that I am not stretched out. Even at my shortness shops tend to want to put me on a bike that is too big - I'm 5' with about a 29ish inseam - they always want to put me on a 48, but my torso needs a 44. I would suggest to anyone who thinks that they are bad at climbing hills and/or has knee pain climbing that they really take a critical look at the size of bike they are riding - a too long bike with too long cranks can kill your abililty to get up hills.

I've also hear that the pros tend to ride somewhat smaller frames than are recommended to the general riding public. A lot of it is to get a super aero postition on the bike that would be hard to achieve on a bigger bike. I'm sure they wouldn't do it if it affected the handling since they are epxected to fly down mountains at crazy speeds. They can, I'm sure, get custom geometries that just are readily available to us though - super long stems are said to make a bike squirrely.