I have thought of getting a HR 500 for a while, and tweaking it a bit to fit me and tame recoil...After reading the info on the net about the HR's, I am a bit skeptical but may in fact proceed with a "useless unpractical, but cool" build.... And yes a 500 because its different and has lotsa ooomph... and yes, you tend to hit what you are aiming at when you only have one shot.
As for bears, yes it would work just fine. As would almost any centerfire gun if you can shoot. Personally, I live up north, o/o of a fishing lodge, and have encountered more bears than most... they really are not hard to kill, nor are they man eating beasts which you have to run and get a gun at every sighting. Of the ones I have seen, 98/100 will run away if you look at them, #99 will run away when you make loud noise after it craps its drawers, #100 will just ignore you. Altho I always use caution, Bears are not the dangerous animal that we have come to believe. The only instance I would be really concerned is when there are cubs around, or a wounded bear is present...
A 12ga slug/buckshot is by far the best if you want to drop one in its tracks, period.... But if you wanna see one run really fast, get close to one, and either bang two steel garbage can lids together, or shoot it in the butt at 25yds with a 12ga loaded with black peppercorns and rock salt...