Oh yes - a few years ago I killed a caribou at 356 long paces with a 17 inch barreled '06 wearing a 2-7 Leupold, one shot. Using a prone position and literally rock solid rest that I built up myself from a few flat slate pieces and my cap for a pad. That was not an "under-powered" scope either.....
True, I estimated the range (pre rangefinder) at 300, but a heart shot works as well as a lung shot. That had nothing to do with the scope's power. It's good when one gets lucky!
Personally, I could hunt with a 6x fixed power the rest of my life and never look back. I'd not feel underscoped to 500 yards. In fact the longest shot I ever made - well in excess of 500 yards- was made with a 3-9 steel tubed Weaver set on 3 power. Long story why. but my eyes were 40 years younger then and certainly seeing the first bullet kick up snow on the hillside below her didn't hurt any for applying Kentucky windage on the second shot, which centered her lungs.
Alas , I only have one 6x ....and several more rifles than that. Tho I love the 3.5-10x Vari-X III that I have on my Tundra gun. It was given to me so what's not to like?
Nothing wrong with the higher powers tho if you don't mind the bulk and weight. Compromises are everywhere.
