I got into S scale a little and know a few companies that make stuff in S scale.
There is; S Helper, Gargraves, and K-Line(if you can find it) for S scale track & switches. K-Line made some S scale items but they are mainly undersized O gauge stuff mounted on S scale trucks.
MTH makes S scale items but I don't have anything current in S scale trains, just post-war A.F. From what I have seen with MTH prices for H.O. scale I am staying away from them.
Not sure but I think the other company making S scale stuff is AMerican Models.
Now about the size factor, I really don't see any advantage to doing S scale because most of the curves that I have found are 42 inch and above. That is even larger than the 036 Fastrac curves by Lionel. Also another factor in S scale is the voltage; A.C. or D.C.
Lee F.