Well, I still haven't killed a brown bear but I have now hunted them for about 20 days in two years and have been very close, although not 5 yards like Scott, to a handfull of bears. My closets calls from this past trip (back yesterday), included one bear walking thru my two shooting lanes without slowing down and another quartering toward me thru my only shooting lane.
I have been carrying a 66# selfbow and I know it is more than enough bow, not even a concern or care. After all brown bears are just flesh and bone like any other animal and not some mystical beast that they are sometimes made out to be and a bow appropriate for that size animal is the same one that one would used for elk and moose, nothing more, and maybe even less cause most brownies are smaller animals than elk and definitley smaller than moose.
I haven't found the ABC Islands' bears aggressive at all in the spring and actually hunted them solo on this last trip. The only act of "aggression" that I witnessed was a small bear turning broadside and puffing up cause he thought the twig snap he heard was another bear, at first. When he realized it was human he acted like all the others and was out of there fast!
I would estimate that 95% of the bears I see in the spring are 450-500# or less but I did have one whopper boar at 35 yards on the last day that I am sure would have squared 9 1/4', at least, and likley weighed 800 or so pounds. A very large animal in the Spring for SEAK.