I think the main reason the disc is used on the track is for its stiffness rather than its aero properties. There are all kinds of tests that show the making the rear wheel more aerodynamically efficient is not very effective at cutting drag. Depending on how much you're looking to spend, an old Zipp disc works out perfectly. I just picked up a 950 for $500 and it already comes with the track hub on one side and freewheel on the other.

I also vote for the pro-lite fiberglass disc as the loudest disc ever.

HED discs are known for their high tendency to flex under stress. I've been told that time trial specific discs are not always good for use on the track.