It seems odd to me. You should be able to do both because if you can't do either, you are likely no good with the other. Your performance should improve, but you shouldn't radically improve by going clipless or visa-vasa. If you have, then you weren't using themcorrectly to begin with.

I swapped to clip-and-straps some time ago to keep things fresh and keep me sharp. I am much better pedalling after practicing in clipless all these months. Clipless let you learn how to "spin" the cranks, you see? Grab with the feet and spin the pedals right? No more stomping down on it. ... But then I wouldn't go touring with em. I am gonna slap on my SpeedPlay for that.