The M50s have great vocals, imho. My only issue with them vs the M22s was that the M22s had a wider soundstage. But the M50s were also not optimally placed. I think I still need to tweak them some more, but overall, they're great. I've never heard the 40s or the 60s so I can't really speak to those. A lot of it does depend on placement and room dynamics, though.

I am the Doctor, and THIS... is my SPOON!