Well, since this thread is already bumped, I'll put this in here:
I am alergic to nickel.
I can't wear watches, because the winding-wheel usually is plated, but nickel underneath. I get a weeping patch of skin on my wrist. Same with an earring back when I was a teenager.
I accidently ordered nickel Swing66s a couple of years ago after 30+ years of SS, and I had a serious reaction on my face at the next 2 rehearsals. It was not an issue on my fingers, as the skin is pretty thick there, but I touched my face, and I got a pretty quick reaction there.
I was going to start a thread to ask if anyone else had this problem too, but it looks like from this thread that it's pretty rare. Just me and Honch so far...