The .460 is a faster cartridge than the .454 - by design. S&W heralded it's super, well over 2,000 fps design. The long - and slow rifling - is best in a longer, ie rifle-like, barrel. Whether it will live up to it's higher speed rating is a question for time to answer. The .454 isn't quite as fast, and generally is heavier. The most KE I regularly shot from my 7.5" .454 SRH was from the 240gr 2,000 fps Hornady XTP's, which were also the lightest bullets I shot. They actually derated them for a while, but increased them back to 2,000 fps in the last few years. I chrono-ed them from my SRH and measured 1,985 fps with a low +/-12 fps SD. At that, they had a muzzle KE of 2,096 ft-lb - not up to the 2,600 ft-lb of the new S&W .500 Magnum, of course.
Ruger announced their 'Alaskans', in both .454 and .480 Ruger, this year. While the .454 is around - including the one a friend of mine bought and 'let' me shoot earlier this year, the .480 Ruger doesn't seem to be in the stores quite yet. It may just be the better choice. I have heard that penetration is important - but so is a large meplate and bullet mass. In fact, the higher velocity .454's and .460's may just be too fast. This may give the nod to the .480 Ruger - actually, just a shortened case .475 Linebaugh. Sure, only 'dedicated' gun shops will have .480 Ruger - probably fewer than would have the .460's, too. The full sized .480 Ruger SRH is heralded as having a less brisk recoil than the .454 version. It may just be the ideal choice for you as close-in protection against big critters - when it becomes available.
Meanwhile, you can't beat the S&W 629 Mountain Gun for all-but-the-biggest critters... a good choice. Mine is forever a .44 Special & Russian revolver. I just got my new 6" 629 half-lug back from S&W. It weighs ~6 oz more than the MG, but should be easier to shoot well with hotter rounds - especially with my .500 Magnum-style grips on it.
Stainz