Common sense says that the ringed engine should out last an ABC or ABN type engine since the ring can expand as the cylinder wears, but it seems like the ABC types do not wear much. I have not managed to wear out any engines of either type in ten plus years. It seems that the ABC engine can with stand a hot lean run a lot better, the head bolts came loose on my Irvine Q 72 and I thought the engine was toast, but after re-torqueing the head, it ran exactly as before. I turned a SuperTigre 51 dark gray and cooked the muffler so bad that the pressed on back end came off, a new ring fixed it right up but it stayed dark gray, it was on a Sport 500 Collective Helo and the pressure line came off the muffler, but it did not quit. I think that all engines are pretty tough.