The screen difference is much bigger than those 2 inches, the 13" MBA is also a higher resolution so depending on what you use it for that can be important - 1440x900 vs. 1366x768.
Do you have any first hand experience going between the two?
I've been in the stores and had a play with both but of course being in the store is completely different to being a couple of months down the line and thinking hmm I could've gone smaller or I could've gone bigger.
I mainly to be honest flick between sublime text and the browser and the terminal. I auto hide the dock and that's about it.
I mean 13 inch MBA is on the refurb store atm in stock so maybe it's a sign to get it. My thing is like I have a 15" MBP so getting the 11" would be a bigger contrast in size as opposed to the 13" if you see where I am coming from.