puttnfool We've had some long discussions about SL irons that you can read through. Long story short, the manufacturers try really hard, through various means, to keep the gaps consistent. Wishon makes all the clubs have exactly the same feel in terms of swingweight, etc. To compensate for gap issues, he uses a hyperflexible face (for lack of a better word) in the long irons and does somewhat the opposite for the faces of the short irons.
Cobra has already come out with a SL set, as well. There are obviously component companies and non-big-name manufacturers who have been doing SL for quite some time.
I've never tried any of them, but the idea is kind of interesting to me. I know Rickochet was, at one point at least, playing the Wishon Sterling irons. He probably still is, because he was saying that he really liked them.