Being a big bore revolver lover, I have the Taurus 6 3/8" .454 Casull Raging Bull, Ruger 7 3/8" .480, S&W 8 3/8" .460XVR, S&W JR 5" .500 Magnum, S&W 6 1/2" .500 Magnum, S&W 6 1/2" 629 .44 Magnum as well as other .44 Magnums.
If you're used to shooting the .44 Magnum, I'd personally get the S&W 8 3/8" .460XVR.
To me it doesn't have that much more recoil as my S&W 8 3/8" 29-2 .44 Magnum.
And as you said, with the .460 you will also be able to fire the .454 Casull as well as the .45 Colt.
Fireing the .454 Casull is a bit more powerful than the Ruger .480.
But I feel you'll have more enjoyment with the ranges of rounds with the .460XVR.
Also, just for target shooting for fun, firing the .45 Colt won't cost that much as the .460 ammo.
Also the .454 casull isn't that expensive.
But you will need to also get used to firing the .460 ammo which isn't that bad, a bit more recoil than the .454 Casull.

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S&W .500 Magnums RULE !