Rx8s are not unreliable ... the engines have so few parts there is nothing to go wrong. The down side is they don't start when they suffer from low compression, unlike a piston that just looses more and more power as it drops.
Rx8's only go wrong once, and it costs £2500 for a rebuild that if you service it properly will last 80k
Compare that to replacing diesel parts and dual mass flywheels and it's comparatively cheap.
The only downsides of the rotary imo is the lack of torque means the car is only fast when wound up, forget being a twat at the lights. It drinks fuel like a 500bhp car with none of the power and it eats cats like nothing else half the fuel you put in comes out the exhaust