Nuts....well I respect your opinion...but I have seen plenty taken with small calibers...as far as bear with a .223...yes I would IF I had shot placement on my side. Please see the attached link on wher I base my experience. If you feel that using a monster caliber makes you feel good then do it...I honestly believe there is nothing in my part of the country that I need to be hunting that a 6mm caliber wont handle.
http://www.bigwoods.ws/bwhunting.htm