Should I upgrade?

Hi! I have managed to find a buyer for my 11" Macbook Air mid 2011, the basic model then. I bought it for 980 Euros back then. This buyer is willing to pay 600 Euros for it, leaving me to just spend 460 Euros (University discount) for the base 2013 13" Macbook Air.

Is it a good upgrade? Would you recommend it? The thing is my 11" Air runs smooth as butter. It doesn't give me 13 hours of battery and has a slightly smaller screen, but apart from that it's the best laptop I have ever owned. I just don't want to spend that money for a "passable" upgrade.

Thanks for your help!