A curved toolrest was one of the first things I bought a zillion years ago. Not even sure where it is now I just know that as I improved so it's shortcomings and needlessness became apparent.
My advice? Stick with your long and short rests, its practice you need not 'stuff'.
On the faceplate question get yourself a handful of nuts from a fixings specialist and bury each in a bit of wood with 2-pack adhesive. Hey presto the basis of any number of faceplates/friction chucks etc. Almost cost free, whats not to like?
The one proviso is that the nut itself MUST tighten onto the face behind the thread on the spindle. It is this face, not the thread, that provides the accuracy.
All the best with whatever you decide on
Brian