i should have added though that after a few grand of 38spls in my 357mag that i have no problems though after shooting a few hundred 38s the 357 do take a more pressure to seat because it you want to seat them you have to push out of the way the fouling from the 38s.
though now that i think about it ive not seen a gun with worn chambers at all so i have to say that i think the problem is more theorectical than realistic. i suppose with a lot of hot rounds it might be possible but that would depend on the steel. i say get it and dont worry about it