I never played with a true muscle back design, but I gamed Wilson Staff Gooseneck irons for about 15 years and they were as good for me as anything else I've tried, which consists of: Ping clones from the mid 80's, forged cavity back components (can't remember one brand, the others are Alpha), and now Ping Raptures. I'm not a good scorer (my scores generally fall between 86 - 95, with most shading toward the high end due to infrequent play), but am actually a pretty good iron player relative to other players in that scoring range. I've only gamed the Pings for the past half year and they were showing promise of being slightly more consistent in that it takes intentional effort to make them curve. Good if straight shots are required (me), not good if you play with enough skill to maneuver the ball around obstacles and hazards or work the wind. My skill is low enough that I'm better off with a straight lay up to a safe area than I am trying to curve the ball even though I executed some of those type shots on occasion with the Goosenecks. I would hit them very consistently with a draw, but the amount of draw wasn't consistent. I think if game improvement irons offer any help it is only in that I don't unintentionally curve the ball as much. They don't seem to be easier to hit solid shots with as far as I can tell.