21.08.09
I ordered both a GX922 and a m510 6 iron to test.  While both clubs were excellent in quality and build, the GX922 was more forgiving for my game in it's current state.  Mis-hits with the GX922 were few and far between, and were still in the short grass.  The club feels great and breeds confidence, which I believe is a big part of the game.  Balls fly with a great trajectory without a lot of spin.  I was so impressed, I'm buying the rest of the irons to complete a set.

20.12.08
I am a seven handicap and I  recently ordered the 3,4,5,6 irons in C510 and 7,8,9,Pw in M510 forged.  I played with them for about three rounds and found that the cavity backs were a little more forgiving and I could work the ball a little easier.  I also felt that I could feel a good shot a lot better with the cavity backs so I returned the M510's and filled my set with the C510's.  I  was looking for a forged blade and I bought some Cleveland CG1's about a month ago and returned them recently).  I find that getting custom fit clubs is priceless and these clubs hit just as good and even better. than the Cleveland irons The M510's are awesome clubs but I found my game and swing were not ready for a muscle back iron.  Customer service from Gigagolf was awesome and got my clubs exactly one week after I ordered.  I will definitely be a gigagolf customer for a long time.

30.10.08
I've been playing with these clubs for about 18 months now and I'm really impressed.  I'm playing the I should have said C510 3-6 and M510 7-PW, all in stiff featherlight TT gold shafts.  The consistency and control are outstanding - you don't need to over-compensate to shape a shot or to hit to a distance that falls between clubs.  If you're a good ball striker with a reasonably consistent swing, these clubs will get you closer to the pin more often.I don't change my irons often, and played my last set (Hogan Edge forged cavity backs) for about 15 years, so I was prepared to pay for branded irons.  But I wanted the opportunity to mix forged cavity backs in the longer irons with muscle back blades for the scoring clubs, and the custom fitting system sealed the deal.  The whole package has worked out great, the irons are top quality and the custom fit allows me to swing more naturally and thus more consistently.