The RX-8 is a fantastic car. I spent the last couple years driving around the country in one for SCCA Solo competition. It never gave us a bit of trouble on the road. The owner had a problem with the coil packs early in the car's life - fixed under warranty. But otherwise, we hammered the ******************** out of that car for two plus years and it never stopped ticking.
Nevermind that it has a stiffer chassis and a far more advanced suspension than the Boxster.
... that said, the rotary, to me, is not a good "fit" for the boxster