I know this is an old thread, but since I'm the OP, I'll revive it!
I did attend the PDS at Buttonwillow in Feb '15, but was not all that impressed with it as a driving school. We did get classroom time (for the newbies only; there were two run groups, one for more experienced drivers), and some seat time with instructors, but the former was really basic, and the latter was hit and miss (I find the quality of instructors to be the most variable thing about any kind of performance/track driving school). What's more, they advertised skid/car control exercises and also, iirc, threshold braking, yet neither happened! The skid pad was apparently open, but students were on their own (that is, no instruction was offered).
They are doing it again next month. I am actually thinking of going as it's a good way to get some track time with a proper/safe organization - e.g., they do a proper tech inspection, not this self-tech BS that many track day groups allow.
My two cents. Maybe others have had a different/better experience?
05 Elise, ST, sports, touring, hardtop, DBA 4000 slotted discs, Ferodo DS2500 pads, Sector 111 gpan3, EP Tuning Quickrack, Pro Alloy rad, DS brace, HnT pad, front and rear tow hooks, CG lock, ORE double cup holder (caffeine for track); '86 911 Targa (sold); '68 MGB (being restored)