I think most people are allergic to nickel, or so i've been told by m' doctor. I get a crazy, oozy rash from my belt buckle if I don't have it synched up in a certain way. I use Ken Smith stainless steel strings, and they work great. They don't sound as bright as nickel strings, but stay crisper longer.
i use the roto RS66LEs to avoid the rash. and man you have no idea how hard it is to find a stainless belt buckle that's not some ridiculous design