I have a .44mag SRH. That's my largest.
I fired a .454Casull. That is the largest I've shot, other than a .50AE semi-auto.
The .454 isn't as powerful as the .460 or .500, nor the .475/.480 sizes [or so I understand].
After my experiences with the .454, I have no desire for anything larger.
Why? I want something I enjoy. Not something with max power, but the max I can repeatedly fire for fun.
I can put 50 rounds of PPU .44mag 240gr HP through my SRH without significant concern. I am about as accurate at the end as the beginning. And that is a round producing around 1200 ft/lbs of muzzle-energy. Use the more 'normal' rounds at 750-800 ft/lbs of power and it is even more fun!
I shot a range-mate's .454 Freedom Arms revolver, putting all 6 rounds in 3" at 10 yards. I don't think that is good, but it is acceptable: especially for first time.
Life saving? Yep.
However, after the cylinder was empty, I was done. I realized I would only shoot 1 cylinder per trip if I had one.
So, my decision is based on my 'fun' factor.
I don't handgun hunt, nor do I carry one for personal defense in bear country. Where I am a bear-load .357 will probably work [black only, at most, and cougar].
So: no need for more than .44mag and don't find it fun.
Cost per smile: too high!