You are right about the rusting. Nitromethane attracts water from the air and thus water gets into your engine. But as long as you don't forget to run it out when your done flying for the day, rust won't be a problem.

I think I'm going to avoid all the rust and cost problems by switching to gas anyhoo... Can anyone say U-Can-Do-3d-With-an-RCS-140?

Or maybe an Mvvs 160....Hmmm. :devious: