Originally Posted by StanSeven
Wheels can be different in two ways (excluding durability). One is weight. Lighter wheels make a very, very small difference in climbing, especially for long and steep hills. The other is aerodynamics. Aero wheels can improve performance. For example, deep aero rims can knock off quite a few seconds on a 40 km tt, perhaps a minute or more. So, for most practical purposes, wheels don't matter at all unless you are concerned with performance climbing or gaining precious seconds in a timed event or race.
I think you are minimizing the weight savings too much. When I upgraded my wheels earlier this year, I shaved off almost a pound and instantly made my climbing easier.
Also, you forgot the ride itself. A good set of wheels will be noticeably smoother. I do agree though, that you should pout some miles on the stock wheels before upgrading.