Interesting points. I've been data gathering, and I'm not sure if UK sleepers really 'poke out' of the ballast as much as they do in Camber's assets. For example:
I think I might use 2D track, and tinker with the textures.
Horgy
Essex Radar: "Ryanair 445 Good Evening, Information Charlie current, confirm aircraft type is B737-800?"
Captain: "Well, we don't have anything else do we?"
With correct maintenance there shouldn't be much sleeper seen outside of gravel bed anywhere, doesn't matter if it is concrete or wooden. But clips which are fastening together rail and sleeper must be clearly visible.
thats what i mean. maybe the shape of the concrete ties makes them appear to stick out more, even if they are at the same height as the wooden ones.
if the sleepers are part of the ballast texture and you create the shape of the ballast in the right fashion you can even leave out the supersleepers altogether with convincing results. i'll do a screenshot later.