Mine started getting slightly tetchy with age and used to ghost shift. Remember all that keeps it in gear is that spring. On a conventional mech it is the chain tension.
Swapping to a conventional mech stopped the ghost shifts.
All mechs can ghost shift if poorly setup or if the cable is in poor condition. I don't see how rapid rise is any more prone than a conventional mech. It's the spring pulling on the cable that defines the gear the mech is lined up with in both cases. If the cables are old and gummed up then the spring isn't strong enough to pull all the cable that is released by the shifter. Your thumb however, when pulling cable back in, is strong enough to pull all the cable back, plus the shifter won't click to the next index until all the cable is back in anyway. Thats why some times you have to go down two and back up one. Or in the case of rapid rise up two and back down one.
Rapid rise is kinder on the chain when shifting into lower gears (gears with more teeth) underload, which people tend to do when riding up hills. With a conventional mech you are pulling cable back in so you apply pressure to the shifter until it clicks into the next index and the mech HAS to move to the next gear which puts alot of side load on the chain (eventually pulling the outer links off the pins and causing it to snap), it shifts and makes bad noises whilst doing so.
With rapid rise however you are releasing cable as you shift into a lower gear meaing the mech won't move all the way across to the next gear as it is only the fairly weak spring pulling it over, not your thumb and the cable. The side load on the chain therefore isn't nearly as much, the shift occurs when the ramps come round and its all alot smoother and nicer. Shifting into higher gears under full load on the other hand is not as smooth with rapid rise but how often do we do that. If we are shifting into a higher gear then it usually means we can afford to back off the load when doing so.
In my opinion rapid rise actually makes more sense than conventional and is probably the way it should always have been.