S2K's dont hold the abuse like a Miata can. I have heard of far fewer diff and tranny problems for the Miata then i have with S2K's.

Besides, when the time finally comes to replace the top (which it will, or soon if something were to happen ), replacing the top on a Miata is faster, easier and cheaper then a S2K. The top is manual, less likely to have problems and its really easy to operate for being manual. And wheels are easy to find and you dont have to pay extra for fancy staggered setups.