As someone who used a Mac Air to edit photos during a recent trip... DON'T. It works but it's slow as hell and chokes the system really badly. Takes forever to run actions, save PSDs, convert... basically anything you need to do in Pshop is 80 million times slower.
My advice would be to just simply be patient, stick your images on a harddrive and bring them home with you. Unless you're prepared to pay big $$ for a Macbook Pro with decent specs, it's not worth the annoyance.