In general, I believe you are correct (though I haven't heard the M50s), but much depends on the listening environment. I have my M60s upstairs now and they sound positively warm and rich in that room (mated to some older Onkyo DACs).
All I ever listen to is the same Reggae for Kids disc right before bed time, but Hakuna Matata has never sounded better!
It's kind of like using a Ferrari to deliver pizzas, but I can't bring myself to sell them.