Lack of bullets for the 480 is a rather lame excuse IMO. You can find 275 to 420 or so in a variety of designs quite readily. If you can't blow a 4" hole out the back side of a deer or run a bullet fully lengthwise through a bear with one of the them, perhaps you chose wrong, not lacked enough selection. Besides, you can only shoot them one at a time.
Of course, you can get a 454 and use it for a 45 Colt, but why when there are already nicer Colt chambered guns already available? Besides, even the "Super Colt" doesn't shoot a 400 grainer well, and they are a bullet to behold even going at stately velocities.
Then again if hunting with a revolver at 150 yards is your deal, the 454 probably makes more sense.