Sure, but again, though, not as easily as most pistons. I did 2 rebuilds on mine in the time I had it. I put about 90k on it and it was at 80k when I bought it. Apex seals blew once, even before it was time to replace them, and even despite that I took care of that engine religiously. It wasn't warped, those engines just inherently have issues. I used mine as a daily driver, and when you can't rely on your car to get you to work, it's a pain in the ass.
As for the rebuild, I would say it was easier to rebuild than a piston engine the second time I did it. The first time, it takes a bit to get your bearings. I've rebuilt many pistons, so switching my brain over to working with all the small moving parts in the shell of the engine was a bit hard. The second time, though, it took me half as long and was, indeed, pretty easy.
Upgrades, sure, the RX7 has them, but the majority of them that the 944 doesn't have, (i.e forced induction) take so much life and reliability off your engine, it's comical.>>18242441
It was more of a pain than most cars, yes. But, if you're dedicated and have a fair bit of money lying around, I don't see why it wouldn't be feasible for someone who's knowledgeable enough. The car I got was in pretty damn good shape too. You get into the habit of checking oil and coolant at every fill up (I didn't premix), you start looking at your temp gauge more than your speedometer, and you always have a rebuild kit handy because you know it's going to be inevitable that something blows. It's weird to get used to at first because the car is like a needy, bitchy girlfriend, but once you fall into the rythm of always taking care of it, it's not too bad.