I had a 2011 13" 4gb/256gb i5 for about two years and loved it. Last week I sold it to a European friend as a "sweetheart deal"

. She travels a lot and it's a huge upgrade from her terrible Windows netbook.
I have started doing video again and wanted to upgrade to 8gb and 512gb. But I agonized a bit over the 11" vs 13" dilemma. At home, it's always plugged into a big monitor and external keyboard, so size doesn't matter there. But when travelling, I have wished I had the 11". For me, the screen size trade-off is reasonable on the road. If I was using it every day away from home, I might feel differently.
Cutting to the chase, I ended up getting the 11" i7 8gb/512gb model from B&H since I was staying in NYC for awhile. It was almost up to a coin-toss, but decided that saving $100 was a good thing.
On paper, the weight difference doesn't seem that great, but it sure feels a lot lighter. I can carry it around all day and not even realize it's there. Those fonts do look mighty small though - but my eyes are old and I need some new glasses.
The greater runtime on the 13" was tempting, but I was able to get through a long day with my 2011 13" MBA. Apple rated the 2011 machine at 7 hours and the 2013 11" MBA at 9 hours. I definitely notice the additional runtime on the new machine, so it's still a nice upgrade for me.
I'm very happy with my choice after about a week. And my friend just loves the 2011 13" MBA. Life is good. Just returned home from NYC and spent a little while last night messing with drivers, etc to get everything working under 10.8. Migration asst really took care of almost everything though. The only thing I don't like is iTunes 11 - but that's a topic for another forum.
If you're on the fence regarding 11" vs 13", I suggest you spend awhile in a store playing with both. For me, it's just cool to have such a powerful computer in such a tiny package. Last time I felt this way was when I got my Powerbook Duo... when was that? 1995 maybe?
