I have actually never heard that you shouldn't CC with a conversion.
I have heard the opinion stated that your EDC ought to be as close to stock as possible (especially in regards to the trigger assembly) in order to avoid legal entanglements should you have to actually shoot someone with it (I agree with this philosophy only insofar as trigger pull wieght is concerned: an overly light "hair trigger" may be good for competition but becomes a safety concern with EDC).
I have also heard of people shooting competition with aftermarket barrels, but do not know if these were conversions as well.
I've read multiple threads about it.. I think it has to do with the recoil spring assembly. My gen 4 g22 has the new rsa and I've put about 1,000 rounds through my LWD 40-9 conversion barrel without a single malfunction. Love it