If you ride FG frequently around town, I don't think, with the GI you have, you should have too many problems on moderately steep hills by standing and mashing..
I rode a FG on a year's worth of Century a Month, completed 400+km of PBPp in 2007 (other issues, not the FG, forced the DNF), did 50km return shopping trips, and toured on it with a 39-17 set-up. I am reasonably old, but I was able to cope with up to 15 or 16% grades before thinking that getting off was the better part of valour.
As to the lowish gear and riding downhill, yes, I used to get up to 130+rpm cadence, but I also used my brakes to moderate things. I never bothered with braking through the pedals... I value my knees too much.
Last edited by Rowan; 10-15-11 at 05:04 PM.