I just got the 11 Air this weekend and I really love it. In terms trading in your MBP, Im not sure if you want to do that if youre photographer. As you probably know, the air wont handle heavy duty photography jobs like the MBA does/ But if youre attracted to the light portability of the Air, then yes most definitely get the 11, or the 13 if you dont mind spending the extra money.
I got the 11 because I knew I would only be using the Air for like a few hours per day, because I do most of my work on Mac Pro. I wanted the Air so when I get out of the house and work and for when I travel on occasion. But Im certainly don't expect it to help me complete large production jobs. Its great for writing, small GarageBand productions, and short run photo editing.
If Apple had priced this entry level Air at $799, it would have made a killing over the holiday season. None-the-less, Im so jazzed about the cool design of the Air. When I look at other notebooks I just shake my head. Most are down right ugly. The MacBook Air just inspires me.