The main difference between RTS I & II is in the mecanical shutter speed (none on RTS I, 1/60 on RTS II): the RTS II camera could work even if the battery expired.....
In any case, I bought my own RTS I in year 2000, after about 15 years of use by a professional marriage photographer and just serviced....still works and I just loaded a BW400CN yesterday, to shot with his Planar 1,7.
The camera is beautiful, well built, the meter is sharp, the shutter release is smooth with few vibrations (even if loud in noise) and the finder bright a lot (better than a Nikon F, I previously owned).....don't know why, it's my wife favourite film camera 😕
The only real issue is that the shutter is electronic and I don't know anything about spare parts avaiability......