ML's are very good speakers, and yes your experience could also be due to room variations between yours and the demo room and your thought about the costs. Sounds like you might be inline for M80s if you liked the upper frequencies a little more pronounced as the ML's did.
Try to listen critically to the M60s at louder volumes, start low then increase to say 85db and up. Listen how the sound changes when you reach a certain mark on the dial. I have found them to 'open up' and the upper end becomes more apparent when more power is fed to them, this may sound closer to what the ML's sounded like. This is also what the M80s sound like to me at all volume levels, this is their gift to us M80 owners
