Those things are so tiny that they get good performance out of a fairly low powered motor, and they stick to the road like glue...that's a great fun/track ride if you can fit in the thing.
A guy who worked for me had one and he wanted to drive me to a customer visit to show it off...it was sprinkling and he had to keep the top down. I was worried that my head was going to burst right through the roof or my neck was going to break from a pothole...I could not even remotely consider owning one.
Yeah, for SCCA stuff those cars are hard to beat. S2000 and Miata are what most of my friends who do that drive. Once you get a roll cage in there and some decals on it, will be much less Dorothy friendly!