I normally shoot 50 - 55 lbs but this year shot most of my 3D's with a 44# Crow Creek 3 piece longbow, mainly because I can't shoot a lot of arrows comfortably with my heavier bows - and decided to pig hunt with it. I shot one pig, about 80 - 90 lbs. with it this year. I used the CE Heritage 150's, cut 29" with a 160 grain STOS. Those arrows weighed around 540 grains. The arrow zipped through the pig and shattered the leg bone on the opposite side. I was impressed with that performance.
One thing I've found is the lower weight bows don't come off the fingers as good as the 50 - 55 pounders, but once you get used to them its no problem.
RC - sounds like your buddy John has proven how effective a 45 lb. bow can be....I don't think you'll have any problem shooting out to 25 yards with the lighter weight...I have found that beyond 30 yards or so my arrows drop a lot - because I'm shooting over 12 grains per pound with the CE 150's, but for hunting ranges that's not a problem. By the way - what broadhead does your buddy John shoot?