Don't let Whitworth's prejudice against the 500 sway you. You've already got the 4" 500 and it's really not much heavier than his Toklat suggestion. You're going to notice carrying either one. The difference is negligible with a good holster. And that extra 12 oz will let you send a heavier wider bullet as fast or faster with similar recoil.

With that said, your best bear gun is the rifle your partner has, and his is your's.