Green Gas vs. Propane? (airsofting)?

Are there any disadvantages of using propane instead of green gas in an airsoft gun? I know that propane smells, and I know that you need to add silicon to it or your o-rings will dry out (among other things). Besides these two things, are there any disadvantages of using propane? It doesn't make much sense when propane is so much cheaper, but I don't want to damage my gun.