ORIGINAL: DMIt's really all about bullet performance, NOT caliber, and dam sure NOT all about high velocity!!!
A 500 S&W is a lot more gun than, say a 270 with too light a bullet for the big bears. I'm NOT saying anything against the 270 though!!
I've shot big bears, good penetration is more important than high velocity and high energy!! A good bullet with a good SD is needed above all else, (assumeing at least a decent cal.) that is "if" you want to break heavy bone!! That's something high velocity bullets don't do as well. This may be why one writer recomends one cal. that another doesn't!!!
With the RIGHT bullets, and close ranges, i wouldn't have a problem hunting big bears with a 30-06, or better yet a 7mm mag with 175 grain premium bullets. I did shoot one with a .264 win. mag. though. Drilling Man
You make several good, valid points here, D.M. Whenever I hunted in Alaska with my .270 Win., I ALWAYS carried ammo loaded with either 150 or 160-grain Nosler Partition bullets. This was in the days before the other premiums!