I recently purchased mirrors for my mirror-less R100S. I bought the matte black, short stem bits just because I like them better than the "insect antenna" long stems.
Motobins was my choice of vendor due to their large selection of matte black and chrome, long or short stem mirrors. The clincher for me was the fact that the mirrors I bought are manufactured by Bumm, the OEM supplier to BMW. The prices are way below BMW dealership numbers -I looked 'em up!
Like Barry, I'm slim which helps out with the mirror's field of view. On the other hand, old Phorqs is attempting to fit a pair of those electric, slide out, Dodge Ram truck mirrors that will make his GSA about six-feet wide.
I kid the Crunchster but he has, like me, become a gym rat since retirement. It's those Shiner Bock 12 ounce arm curls...