I actually did make a muslin for the compression shorts, and found that I needed to make the swayback adjustment; it fitted really nicely after that.
The skirt top layer is a Wazoodle ProCool Wicking Pique, and the compression shorts are a technical wicking fabric that I found at C&M Textiles in Ottawa. You can see the wicking side of the fabric in the interior shot below, it's really soft.
The only thing I did differently from the pattern instructions was to top-stitch the side seams in order to keep them flat (above left), and I cover-stitched the waistband seam too for the same reason.
This skort went together really fast, and I'll definitely make another one with some more fun fabric for the skirt layer.