I think Big Jim is spot on. Here's my 2 cents...
I shoot heavy bows compared to most, but not as heavy as some....anywhere from 60 to 80 lbs. Here's the thing...I've been shooting since I was 7, and this poundage since I was 18. I can shoot a heavier bow now, than I could 20-some years ago! It's all in how you practice. Too many of us, I feel, shoot too many arrows per session, without rest between sessions. It messes with our muscles, our joints, and our heads (since accuracy is 90 percent mental, this is important). If your gonna shoot 3-d targets all day, by all means go lighter. But heavy does have advantages.
The "trend" these past couple years has been to say "modern" advancements makes it OK (to shoot lightweight for hunting)....but modern bowmaking really is not that much better than it was three decades ago....a few FPS doesn't mean SQUAT! There are SO MANY other variables that affect how efficient your shot is (notice I did not say bow)....and the truth is, the lighter you go, the more responsibility you have to make sure those other factors are dead nuts right on! You guys shooting 40lbs are setting yourselves up for wounding and losing a lot of critters, IMO over time....there is no way you can CONTROL all the variables. That's why it has always been a kind of unwritten rule to shoot as much poundage as you can shoot accurately. When I hunt, I don't shoot hundreds of arrows...really?!! I've got other things I'm concentrating on.
If you go lighter, you will be shooting lighter weight arrows, weaker spined shafts, more subject to cleaner form issues, and your accuracy, under pressure, has to be spot on...while you are likely breathing like you just ran a block into the wind! Break it all down and examine it. It's not as simple as just improving accuracy at the target butt, shooting groups....its reducing your "fudge factor" in arrow flight at impact, in the efficiency of your broadhead, in the momentum of your missile, in the unpredictable crosswinds that will cause the back of your shaft to drift....there is just too much that has to go right, with a lighter settup, to work every time. Extra poundage allows you a heavier arrow, a stiffer spine, a cleaner release, overall a bit more momentum....and that extra "umph" peace of mind thing.
Too many of us are using the "modern" material and design thing as their excuse to drop weight IMO... Make the decision to differentiate between targets, and hunting....and educate yourselfs about your responsibilities to the game, to the pastime we enjoy, to the way in which you practice. There is a lot there.
I'm 52 next month, and I can shoot heavier bows now than I could when I was 30...even with both elbows having tendonitis, and arthritis in my right hand.
BTW...50 lbs in my book is not a light bow, really. Dropping down in the 40's is getting pretty light, and will demand your attention to these things. Ultimately, you must shoot what is legal, and, in you mind, what is ethical.