A Boxster GT4 would be quicker. Lower center of gravity, same power, same proportions, perhaps less weight if they went with another bikini top. Other than track regulations demanding a fixed roof,
a Boxster would always have the upper hand on turn in which makes me wonder why people get more excited about 981 with a fixed roof getting the big power. But at the end of the day Cayman and Boxster are merely variants of the same car.
However either at $125K might be tough sell if it parks next to a
C7 Z06 (with all the track goodies already addded) or worse, has to give it the point by. And I'm not in the market but 996 Cup car can be had for that kind of money as well.
http://i1.ytimg.com/vi/lv2F1slIyWw/maxresdefault.jpg