DS2500s kick out red dust for the first 500 miles or so for some reason, they're actually pretty good on the dust after that.
Alcon also recommend & factory supply the DS2500s for their kits. They do also have an "approved" list including Mintex, Pagid and Hawk (very well respected in the States, if not that well known over here yet). Given both suppliers work with WRC, F1, Indy, GT racing teams etc, I think that speaks volumes of the standards that both them and AP Racing expect from a pad.
I've also got some DS3000s for the track, they're fricking nuts, but difficult to get enough working heat into anywhere else.
I'd be interested to hear what pads the VW Cup cars run, as they all either have AP, Alcon or VWR brakes. Fancy asking them next time you speak to them, Robin?