Problem is the metal pieces that get in the conv. If its a l/U then the metal could get embedded in the lining and then as it wears release it into the fluid and block valves and passages.
Also the convertor has to be cut open to be cleaned out.
About the only hard part breakage scenario in a 200-4R that you might get away with would be when the intermediate shaft snaps with a clean, flat break. That's about it.