I would do yourself a favor and hit the JPX 800 PRO irons at that same time...I am a 7.7 handicap and consistent ball striking is my constant challenge and for me I found the JPX 800 PRO iron a great mix of Mizuno buttery feel and but with forgiveness on those days when I am struggling...believe me I could swing the MP 58 irons (as many of my friends tried to talk me into them) but I could not argue with results...how I tested irons (MP58, AP2_710 & JPX 800 Pro) was as follows as I think this process helps get you in the right sticks:
Get the clubs set up to as close as possible to your specs...obviously
Hit on mulitple days (do not hit only one day because if your swing is in the slot that day you might as well buy the MP 68 irons because when a single digit is swinging well they can hit pretty much any iron)...remember this is a game of managing your misses...
Anyway more specifically I would hit them for two days in a row...then I would sit out a day...then go back and hit them for two more days...what I found was that one of those days my swing was not in the slot and the true forgiveness showed up in distance control (which to me is the most important thing as it relates to forgiveness)...meaning if you come from the inside...get stuck...and don't get out of the way so you can release your hands you are going to hit a shank "no matter which club you have in your hand"...that is not what I am talking about...what I am talking about is when you know you did not put a good move on it and you still had enough to get on the green...that is were scoring is important and where the right iron can make a real difference.
PS Charles Howell III tested the entire Mizuno line upon signing with Mizuno and he has the JPX 800 pro in his bag...maybe for the same reason I do???

Edited by i-Guy - 3/8/11 at 7:05am