Well, I used X-shorts for four years with the Fusion. They work fine, and have big pockets. I may still use them in MX; I'm not sure yet. But shorts are one more thing to pack -- or forget; and you can even have them with you at the dive site and forget to put them on. It is a bit of a pain to pull them on over the suit, too . . . not a big one, but a small pain. I have to admit I am LOVING having the tech skin with the pockets, and not having to remember or deal with the shorts. The pockets aren't optimal, but they are usable.
I could see myself using the tech skin at home, where I don't put a lot in my pockets and don't access the stuff I have very often, and using the sport skin and shorts in MX, where I have tons of spools and markers in my pockets, and use them constantly.