This is an old thread, but just wanted to drop in my experience. I shot an 80lb bow for a couple seasons. I injured my shoulder two years ago when a log rolled the wrong way while moving it...long story. Anyway, I definitely couldn't pull 80lbs anymore. I had to shoot a 41lb bow that season. I did a lot of research on building arrows and what would penetrate best. An arrow with extreme FOC and a Solid Broadhead accounted for a couple pass through shots on two does later that season, and a nice buck. One arrow went through a leg bone. This got me thinking...did I really need 80lbs when a 40lb bow shot through a leg bone at 39yds?
I now shoot a 60lb bow...and sometime the same 40lb bow. My arrows weigh around 500 grains, the majority of that weight in the front behind the insert. I've yet to have an arrow not pass through a deer. Yes, my bow isn't as fast now, but it's super quiet and my blood trails have been shorter.
Most new bows are so efficient, that it doesn't really accomplish much shooting a bow over 70lbs.