Its amazing how much this weight thing comes up. I too suffered a shoulder injury a couple of years ago in softball tournament. Up until that point I shot mid 60's no problem. Now I'm down to upper 50's but don't really have the stamina I used to. So I'm moving down some more for next season, probably 45-50 for deer and pigs, saving the heavier bow for working out or moose hunting if I get the chance.
I'd say 5 pounds isn't much difference at the 50-55lb range when your warmed up, but will make a big difference after sitting still for several hours on a stand. Trying a hand full of bows at a shoot is a great idea, but isn't necessarily the acid test if ideal hunting weight is what you're looking for. You almost have to roll out of bed, pick up the bow, draw and shoot to really know.
- eric