Ok, here's the deal. Currently the Wilson Adjuster and its Safariland 560/561 clones are legal for IDPA. The holster rules are frozen until HQ can hash out a new list of approved holsters. The way I understood it is their intention is to NOT approve any holsters that has the ability to adjust the cant to make the muzzle point forward. With the belt loop attachment the Adjuster/560 series can be made to hold the muzzle forward cant. So until the new list of approved holster comes out, it may be wise to hold off the purchase or choose a rig that has fixed cant, either vertical or muzzle to the rear.
For IDPA you can't beat the Heinie/Alessi DOJ and the Rusty Sherrick Rangemaster rigs. They're leather but they are as fast as any kydex rigs out there. And they're classier.