The Performer shorts are cut incredibly high while the Power shorts are cut more like normal shorts. My Power shorts are from a few years ago and the chamois is much like the Castelli chamois (red and like the ones MP bought). Hmm, I'd have to go check the size. I don't recall buying a size up. I think I only do that for Assos.
V, have you tried the Giordana shorts with the W3D OF chamois ? The pad is similar but not the same as the Assos so it may be missing padding where you don't like it. I'm so overloaded on shorts now that I decided not to get a pair after all. I think that chamois is in several different style shorts from Giordana.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.