At some stage paintwork is going to get scratched, unless there's a layer of helicopter tape or vinyl on the top. Mt brompton is covered in helicopter tape which actually increases the depth of the gloss, but I don't think there's a transparent tape which works particularly well for satin finishes.
When my Dahon Vitesse paint got a bit tired I just wrapped it in black satin vinyl (covering all the logos in the process), and it looks a lot nicer now than when it was new.