My experience:
I broke my mirror stay after a low speed drop. I JB Welded it, and it broke again about a week later. I went to Napa, grabbed some fiberglass fabric, and some high strength 2 part liquid epoxy. I cut a piece of fabric to wrap both sides of the bracket, globbed on a layer of epoxy, pressed the fiberglass fabric into it, and then put another layer of epoxy covering the whole piece of fabric. It was quick set stuff, so I only had to hold it in place for a couple of minutes before walking away from it. This was only about 5-6000 miles ago, but it seems to be holding up very well.
I'm not going to kid myself into thinking the bike will never take a nap again. I also switched over to the FZ-1 mirrors, and put on a set of engine and bag guards. I'm fairly certain that if I were to replace the mirror stay, the bike would go down again in another week and break it again.