I guess it's not as difficult as a beginner to switch from right-handed to left-handed because you have to basically learn everything from the start either way. It might just feel awkward at first but even right-handed feels awkward at first!
I nearly switched to left-handed playing as I have a circulation problem in my right hand and repetitive motion (such as strumming) isn't good for it. But silly me stuck with right-handed playing in the end.
As for disadvantages, I read somewhere that one of the problems (apart from the one 737blues mentioned) was that it's more difficult to play "on the spot" with another guitar but yours, as most guitars are set up for right-handed playing. But that's not such a big problem, in my opinion! Good luck
