I believe that they are one of the best blades around at the moment,been dying to try them out. Do you own a set of Mizuno clubs and how do they fair against the rest of the pack. Ping,Cobra,Titelist,ect.

I love mizuno irons. There are definitely a cut above the rest IMO. I haven't played a muscle back model, but have played the JPX-800, JPX-800 Pro, and now have the MP-53's in my bag.

The muscle backs may be less forgiving than some of there other offerings but there's no doubt there are beautifully made, and awesome when struck correctly.

I got to hit the 69s and they were awesome! Here's a link to my review.

http://www.oobgolf.com/content/reviews/product+reviews/1-5302-Mizuno_MP69_Review.html

I have been playing the MX-25's for five years, absolutely have loved em. In the market for new clubs this year, MP-53's are on the wish list, haven't tried the new 59 or 69, think they're probably a little more than my skillset