my MK1 XR2 is running the nitrous.
Your RSi will have been running milage already and its not likely to change.
If you want it, go for it, its nothing dangerous and its nothing stressing for the engine.
Its far better than headowrk and cams for a pure power boost, but youll have the advantage of turning it on when you like, but the disadvantage of not having it on all the time.
its a decision most people dwell on for too long ten convince themselves that its bad cause of all teh crap circulating about it. There is nothing remotely dangerous once its setup, its not even flammable.