Seriously, IF you reload, you can truly make ammo at any power level for the 500. If you don't reload, I believe you can buy 500 specials, 500 medium power, or 500 full power ammo. I suppose you are more likely to be able to run across 45LC ammo in general if you are concerned about availability of ammo which would point to a 460. Also, should you start to seriously consider the 500, barrel length makes a big difference in perceived recoil. I own a 4" and the original 8 3/8" 500. I can easily handle full power loads in the 8", but they are truly stout in the 4". Can't imagine what full power loads would feel like from the 2" 500ES snubby. Have not shot a John Ross model. Also there are Performance Center models (6", 7", 10" hunter).
Good luck with your decision.
Good luck with your decision.