I just bought a 95 RT-10 and love it. I also have an FD, and luckily have never had any problems with my RX7. From what I have seen and have been reading on the board, they are pretty reliable. When they do break, it seems parts are a little more on the costly side in comparison to the RX7. The nice thing is no more worrying about boost leaks, Apex seals and running lean!
I will also say that the FD was my favorite car until I drove a Viper, Do not get me wrong the FD is an awesome car but it cannot even compare to the Viper, once you own one or drive one you will agree.
Back to your original question abour reliabilty, that was one of my concerns when I bought mine and I read several posts and talked to quite a few people that had over 60,000 miles and did not have any problems. I also believe that like any car your maintenance plays a big factor as well as luck of the draw.