Well, if your current speakers are "lacking mids," and have "no highs to speak of," you're probably going to initially hurt your ears with the M60s, because they don't lack either. Be a little judicious with the volume at first. You'll find you won't have to crank the M60s, as you did your old speakers, to hear everything. Just be patient. Give them (your ears) time to adjust to a truly accurate speaker. You're gonna hear things you never heard before. And you're gonna end up lovin' 'em. Betcha!
Wish I could be there the first time you watch a movie with a great sound track.
Just watched The Last Samurai last night and really enjoyed it.
Jack
"People generally quarrel because they cannot argue." - G. K. Chesterton