That depends on what sort of editing you are doing. iPhoto type stuff - the MBA 11" maybe enough. IMO serious editing is better on the 13" screen.
If you want more serious photo editing programs then the MBP 13" would be better long term I think.
You do realise the MBP 13" has less horizontal pixels than the MBA 11" and barely more vertical pixels ? That's a seriously flawed suggestion you just made there.
Screen size in inches means nothing. Resolution is what it's about. A 17" screen and a 13" displaying the same 1280x800 resolution would both show the same amount of information.
Yes I do....
In the end I would rather have lower screen resolution on a larger screen to better see and work with detailed editing than to have a higher res screen that is harder on the eyes.
YMMV, but I would rather have the MBP 13" and the power and lower res screen for heavy editing on the go...