I've seen the theory stated that the 44mag is a smidge more than the N-frame can handle over the long run.
454 Casull operates at the same pressure as the 460 S&W but the 460 outruns it due to more case capacity. 60k+ is ALOT of pressure, especially in a handgun. That's in magnum rifle pressure territory.
Alot of 454 are offered in platforms significantly lighter in weight than the X-frame and I can understand why many folks can't deal with it's recoil when considering that fact. Now when you consider that those Rugers and others offered in 454 are generally heavier than a Smith N-frame with comparable barrel lengths, it makes me wonder how much nastier to shoot the 454 would be from an N-frame (if it could be done).. and additionally, why anyone would want to.
Myself, I think the X-frame is THE BEST platform for such powerful cartridges as they introduce a much higher level of shootability for those cartridges. I get that the short barreled Alaskans are designed and intended to be a more compact close defense weapon, but how effective can it be if quick follow-up shots are extremely difficult in the best of circumstances? Not everyone can be Jerry Miculek, LOL!

And in a package like that with the intended purpose, what can the 454 do that a 44 mag cannot? I'm no bear defense expert, heck, where I live black bears are rarely sighted. But I do pay attention when those who live that life offer advice on the subject. Most of that advice centers around well placed shots, and as many of them as possible when it comes to a bear defense sidearm.
Sorry, didn't mean to go down the "bear defense" road... talking about some of the 454 platforms kinda brought me there.