As far as the MPF, the Actual Vertical CG places a larger roll in the equation, but all aspects of the mass and dimensional characteristics are important to how the club will perform. I would always tell someone that the lower the AVCG is the more solid and forgiving the club will be. That being said, the cg location has nothing to do with you hitting it thin. Would a lower vertical cg make the thin shots possible feel less bad and result in slightly better shots, maybe, but thin is still thin. I would suggest, just being honest here, that you have a qualified teaching professional take a look and diagnose why you are hitting shots thin. Once that is done and your path and attack angle allow you to not hit shots thin, then I would advise looking at irons that had the lowest actual VCG because they will produce the most solid feel on a higher percentage of shots for most players.