Unless you are doing a lot of GPU-intensive stuff, or a lot of photo editing or video rendering, I can't see how the the MBA would hold you back or not allow you to get done what you need to get done.
The jump in benchmark performance from the 2011 MBA to the 2012 MBA was significant. The 2012 i5 benchmarks just as good as the 2011 i7.
Read this review (and the Ars one):
http://www.anandtech.com/show/6063/macbook-air-13inch-mid-2012-review
They'll make you feel a lot better about your decision. I just made the same one - I compared a 2012 13" MBP against the MBA and determined that the MBA was more than fast enough for my needs, and a lot lighter too.
The jump in benchmark performance from the 2011 MBA to the 2012 MBA was significant. The 2012 i5 benchmarks just as good as the 2011 i7.
Read this review (and the Ars one):
http://www.anandtech.com/show/6063/macbook-air-13inch-mid-2012-review
They'll make you feel a lot better about your decision. I just made the same one - I compared a 2012 13" MBP against the MBA and determined that the MBA was more than fast enough for my needs, and a lot lighter too.