I am in EXACTLY the same situation as you. I have been contemplating this as well. I previously had a 2012 MBA 13" which perfectly suited my needs. But I sold it for $800 on CL and go the 2012 rMBP 13" as well with the BB deal ($1199.99 pre-tax and RZ certs earned).
I have been using the rMBP for 3 weeks and admittedly I really like it. It's the screen that makes all the difference. I haven't noticed any benefit, in my use, of going from 4 GB RAM to 8 GB RAM...4 GB appears to be fine for my needs. The processor has a higher GeekBench score, but not noticeable either.
Considering those trade-offs, as well as the battery life differences, faster SSD in the 2013 MBA, and Haswell chipset, it really comes down to the screen that I have to rationalize being worth the extra $300 (33% higher cost) or not. Tough choice...and I have not made it just yet either.