You can run your own calculations. See:

http://www.kreuzotter.de/english/espeed.htm

For my weight range (bike, body(176lbs) and hydration pack + gear), a 5 pound weight reduction gained 5% more speed on a 7% grade for the same power output. You can work backwards with the model and estimate your power output from you parameters and the speed you normally run. Then you use that power output to look at how weight will impact on speed. Note, the tire selection is critical as it impacts frontal area.

This model was actually very close and slightly conservative when I traded off changing from my big touring tires/wheels to my 25 mm road tires and narrower rims. It predicted about about a 2 mph gain. I got at least that average and much more in top speed and when pedalling into a head wind. I believe that was because the frontal area was reduced by 1/2 square foot.

Note the wheel/tire changes saved about 5 lbs.

A lighter person would gain more from a 5lb reduction when climbing than me simply because 5 lbs is a larger percentage of the toal weight.

Al