You guys are doing the gentleman who started this a great disservice. If he is still with us then we are lucky he hasn't given up on analogue and spent his money on CD.
Jonathan Carr is absolutely spot on when he says "The tracking ability of a cartridge depends greatly on the tonearm that it is installed in, and the sonic performance of a cartridge can be made or broken by the phono stage. Regarding both tonearms and phono stages, I have found MCs to be considerably more demanding of the equipment that they are paired with. Phrasing that observation slightly differently, you could say that MMs/MIs make it easier and cheaper to design a phono stage or a tonearm that sounds relatively good."
If the turntable/tonearm are modest then a good MM/MI would potentially be a better choice than a moving coil which may show up limitations in the arm. Lostears is looking at turntable/arms up to $2000 new and mentions the Clearaudio Concept - hence the question on the Clearaudio MM and MC.
Who gives a shit as to whether MC or MM is best, or if some super rare unobtanium vintage cartridge is the bees knees.
The bottom line is that the Clearaudio MC @ $800 is probably better than the Clearaudio MM @ $200.
You would giving the gentleman better advice if you suggested he compare the Clearaudio $800 MC to a Clearaudio $500-800 MM such as the Virtuoso and to consider his phono stage and the cartridge output he requires.
The Clearaudio Concept has a tonearm that is not rigid and I think needs a cartridge of medium compliance.
My suggestion would be for Lostears to arrange a comparison of the Clearaudio MC and the Clearaudio Virtuoso MM at a Clearaudio dealer, preferably with his phono stage.