About 2 months ago, I got fitted and purchased the Mizuno MP-64s and T-4 wedges (50, 54, 58) and absolutley love them. I was in between the 64s and the JPX-800 Pros. Some people said I may regress switching from a cavity back to more of muscle back/blade but I feel like I've gotten alot better with them. Handicap has dropped a stroke so far and I've tied my lowest round ever and sprinkled in few other good rounds.
When you pure them, it feels so solid and the ball jumps. Feel like Ive picked up about 8-12yards---which may also be an effect of getting the shafts matched to my swing speed. My 3 Iron can get real risky on mis-hits but I'm working on that. Shots off the toe go about 15-20 yards shorter but that was expected due to a more compact sweet spot.
My advice--if you are going to pay more money for Mizuno's make sure you get fitted by someone who knows what the hell they are talking about. Have them pop shafts in and out--and if you can, get fitted by a pro at an actual driving range or country club. You and the pro can see your shot shape vs what you see on a screen at Dicks, GG, or Golfsmith to determine which club and shaft is best for you.