Freelunch, the CMR has the same maximum SPL capability as a CMC amplifier. What's lower is its sensitivity, i.e. the absolute output voltage that you'd get from it at any given sound pressure level. Both the CMR and the CMC circuits are sonically neutral, and there's no reason to expect any audible difference between them, at very high SPLs or otherwise.
Also, if sound levels are ever at or near the limit of a Colette series microphone (in either form) on other than a momentary basis, you are exposing your hearing to permanent damage and you should limit your exposure to as few seconds as you can, then probably go see an ear doctor--as I understand it, there actually are some medicines that if given very soon after an overdose of sound, may limit or reduce the damage to the cochlear nerve cells.
--best regards