Hard to argue with mlf16507. Although the design is cavity back with undercut cavity; not having progressive bounce as the loft increases makes it difficult for a high handicap slow swinger to get through the ball without taking getting hung up in the turf. My conclusion is; SL's are good clubs, well designed but better suited for middle and fast swing speeds, where hitting through and taking a divit is not occasionally, a painful experience.
On another note, I am not so sure that having multiple swing planes is a handicap. I find that once you set up correctly for a specific club length, that the swing tends to stay on plane for that length. After all, hitting balls on the fairway with either club requires adjustments for different lies, elevations etc, no matter which clubs you play. Our brains are able to handle the many variations better than you might think. Also, with the SL's I still have three wedges, three hybrids, one wood and one driver that are all different lengths that I have to work with. Even with Dave Lake's 1-Iron clubs, you have at least three lengths to deal with, (the irons, the woods, and the driver). If it were only that simple, I would expect more than just two manufacturers of SL irons. SL's are logical, but then logic and fact are often not the same.
As of the past week, I have returned to my Ping G5's and playing better already. But that's just me.
Best to all.