Had mine replaced under warranty, but you could take it off and get it stove enamelled at a local place, they should be able to bead blast it or similar then coat it again.
Not too big a job. You need to drop the front wheel and the forks out of the bike (i had to change a leaking fork seal anyway) and use a heat gun to melt the locktite on the nut holding the brace to the telelever. Tricky to reasemble as the balljoint on the fork brace is preloaded (can't remember the torque setting about 8nm i think) and has to remain in this position while you horse up the mounting nut 130nm I think!! Its in the manual which I don't have acces to at the moment. BWM have a special tool for this. I used nail varnish to mark the position of the ball joint preload adjustment which is via an allen key and used a large spanner to horse up the mounting nut hoding the balljoint preload nut with an allen key. then used a standard socket to torque it up using a torque wrench then checked that the preload hadn't shifted. Seemed to work ok. Used red locktite on the mounting nut. A friend had a similar problem with a an r1100s and got good results by masking everything off and respraying his fork brace in situ
Had mine replaced under warranty with a highly polished brace. That was 2 years ago. I use metal polish on it about twice a year and it still looks like the day it was done.