John, I've had M2s, M3s, M22s and M50s all using the same 1" titanium tweeter and can report that subjectively, the highs from the M50 sound rolled off compared to the M2s, M3s and M22s. I think a possible explanation as to the M2s and M22s is the 5.25" drivers compared to the 6.5" drivers in the M50s. Of course, the M3 uses a single 6.5" driver, so its compliment is similar to the 2x6.5" + 1" tweeter of the M50s. A possible cause for different treble characteristics between the M3 and the M50 is the fact that the M3 does not use a crossover, but rather runs free. In any case, although I liked the M50s very much, the reasons I got rid of mine were (1) rolled off highs, (2) "chesty" low mids - what can almost be described as a 'boxy' sound. I liked the M50s, but could never fall in love with them, not to sound peculiar, but I love the M3s and M2s.
I replaced the M50s with Axiom M60-like Michaura M665s (2x6.5" Axiom drivers, 1x5.25" Axiom driver and a Merak-like titanium tweeter in a hex shaped cabinet). I love these speakers, although I am looking forward to hearing some M60s or M80s.
