Some have reported OEM pads and rotors are fine for a track day. Others have trashed theirs on a track day. I think it very much depends on the track, the mods, tires, weather, and driving style. My OEM pads and rotors were fairly beat up after an HPDE event.
I have the Wilwood set-up, but no track time on it yet (FL is hot and there's no radiator upgrade yet!). Keep in mind that with the $879 price that's probably with the plain (non-GT) rotors and with the BP10 pads. For track duty you'll probably want to upgrade to the better rotors, and have a dedicated set of track pads. That ups the price by a few hundred dollars.
I'd check out FastBrakes and given them a call:
http://www.fastbrakes.com/default.asp
They have different options for the FiST, and the owner is willing to take the time to speak to you about your goals.
Let us know what you decide