Well mate, I am a single figure handicapper , and used to use MP-67. They are still my favourites. Sleek and sexy, able to nip the ball off tight lies and deep rough. I had tried the MP-59, and at first the MP-59 design did not appeal straight away to me, but did grow on me. This is a players club and for those wanting to take the next step up and be more creative with there shot making I urge you to try them (Mizuno do make the best irons with out a doubt, and their forging practices are unmatched). The difference with these clubs is in the slight miss-hits, where blades can be a little unforgiving on even slight miss-hits and may cost you a penalty and a bad hole or round if you let it. The MP-59 bridges that slight miss-hit penalty, and will still get your ball to safety. But you will still feel the miss-hit which is also important (Feed back from your club is always important, even the bad feed back), just where the blades will leave you short, the MP-59 will surprise you in helping you clear that water trap or bunker, and maybe save you some strokes and the round or tournament. I would urge anyone from a handicap of 14 or better to give them a try.
Also try a match up with KBS (FST) Tour shafts, there is no hype with these shafts, they truly deliver what they promise. The smooth loading and unloading of the club is unmatched, and quite often even when your ball has hit a head wind, you think your going to fall short and land in that water trap, but the ball still keeps piercing through the wind makes it where other shafts wouldn't. Be aware though if you are a stiff-flex in true temper, you might want to check an X-stiff in the KBS (Swing Velocity is not the only factor in choosing shafts, if your are a strong swinger or heavy weight shifter (and not necessarily a super fast swinger), you will also load up the shaft quite a lot. So beware even though the KBS fitting guide in the internet says your a stiff-flex, you may actually be an X-stiff. If there is no KBS fitting nearby then I suggest you order one of each and put them in your six and seven iron. Feel the club loading up and unloading (also remember heavier swing-weight clubs will also have an effect). You'll know what I mean after hitting with each flex. Better to be sure and just lose 30-40$ on the shaft flex that doesn't suite you, than not to be sure and buy a whole set of shafts worth over 300$. Also the KBS Wedge shafts are brilliant, and you'll really notices the difference on the in between shots and around the green. If your using a players club you won't need the Hi-Rev, just get the normal Wedge shaft, the feel is brilliant. Enjoy your MP-59s.
cheers Craig