The only reason I could see doing it is, if you really want to. I have owned the 480 Ruger for some time. It will kill just about anything you shoot with it, with a well placed shot in the right spot. Saying that, I also have a custom 475 Linebaugh. Shoot great and kills every bit as well as my 480 Ruger does, but with a lot more felt recoil. The cool thing about the 457 Linebaugh, you can still shoot 480 Ruger's.
The cost to have the conversion done is not cheap, you could pick up a Magnum Research 475 Linebaugh for less, and have 2 guns. But it all goes back to what you want. If you want it bad enough, then do it. I like the idea of 2 guns myself.