This was a brief topic at the table I played with.. My character is a Star Shaman (I think) Mystic, which gains immunity to the effects of space vacuum at first level and it seems pretty pointless when the DM declares that any piece of armor (not common clothing) can provide the exact same protection.. I'd say it should be a DMs decision how to proceed with it, based on how much interaction characters will have with space and the possible risks involved..