You're correct about the snap-ring issue nsx gramma, and thanks for sticking around.
When it comes to the reliability of these cars, there are some notable issues that may need to be addressed (which you can find more info on in DIY forums/tech discussion/wiki), but by and large they're impressively reliable. These cars are getting old, over 25 years now for most 1991s, and any car that old will need a little refurbishment, but with up-to-date maintenance/fluids these cars can go for a very long time without repair. The kicker is that big ticket maintenance items can be spendy for this car (clutch/timing belt/water pump). With a car this age, I judge reliability on maintenance vs repair.
Take for example a 1991 Nissan Skyline GT-R. Not only are you tackling refurbishment, but you're also addressing factory fit-and-finish and poor engineering solutions in the process. The NSX is a well-designed car, and with up-to-date maintenance can be incredibly reliable.