Unless you want to make all of your existing dies and brass obsolete, there's no reason to rechamber the barrel to another cartridge.
There are two cheaper options for fixing a eroded throat:
1. "Throat" it. - Cut the throat deeper, to clean it up. Of course, some people will feel the need to load bullets to OALs that put them right on the lands; while others are fine with a little more bullet jump. It's your call.
2. Set the barrel back. - Pull it, take a small slice off the chamber end, recut the chamber, and reinstall it.
Every throat erodes differently. The most extreme case I've seen was a .223 WSSM that had over 0.300" 'sand blasted' into oblivion by a shooter that would fire continuously, until the rifle was too hot to handle. He bought it new and only took the rifle to the range 3 times, before he had completely cooked it.
