Hey Don, haven't we plowed this ground before awhile back?
For starters, had I one caliber to hunt N. America, it'd be .30-06. That out of the way, I'm by no means a .243 hater. I've had better luck (and cleaner kills) on antelope and deer (both whitetail and mulies) with the .243 than I've had with my .30-06. Or, for that matter, my brother has with his .270. Ballistic arguments pro and con aside, might it be that I'm AWARE I'm hunting with a lighter caliber and more selective with the shots I DO take? And, as a result, those shots are more often KILLING shots than the sloppier ones I'll risk with a larger caliber?
The last elk I shot took a 300 grain .375 H&H through the heart and lungs and still ran almost 100 yards. I knew I shoulda got that .416 Remington or .458 WM!