I have not investigated all the possible mounting locations on the S but I found few (really just one) options on the RT. That is on the bottom of the fwd frame that supports the upper ball joint of the telelever. It works out well logistically for cable and electrical routing. A beefy tie wrap supports it.
I would never opt for anything but the factory switch... it's ergos are perfect. Anything else just cheapens the look of the bike.
