I am against infusions like Reclast for the exact reason described by the OP: if you have a reaction, there isn't any way to undo the infusion. Reclast is a very powerful drug, given that one infusion is supposed to last you a long time. I'd rather take a weekly pill like Fosamax, which so far is working out for me.

I get that some people have issues with Fosamax, though. You're often trapped between a rock and a hard place with these drugs.