McCormack DNA-750 vs Classe CA-M400

I'm debating on purchasing(great deal here on Audiogon) the the DNA750's but wanted the M400's. Has anyone had the chance to compare the two?

Is there other mono-ss-amps I should be considering in the $5000 used range with around 500watt?! I don't think you can do better than those two brand amps.

THANKS!!!