I booked the R8 for our trip in May.
I was a bit miffed that the originally promised Corvette ZR-1 and Porsche 911 GT3 RS were dropped (the GT3 RS in favor of a more pedestrian Carrera S), but my guess is whoever put that list together was told that ONLY paddle shift two pedal transmissions could be used; no three pedal and a stick. So I figured the R8 had the same engine and a very closely related platform to the Gallardo, so may as well save some money my first time out. If I feel like I learn the track, I might put out more $ for the pasta rockets in the future.
I did compare prices to similar events elsewhere, and the prices for the Exotic Driving Experience are rather lower, so it isn't a bad deal. The real catch is that the track isn't too large, so you won't really get to hit warp speed in any of the cars. You will, however, get a chance to wring them out in other ways.