The only reason to buy the rMBP is if you need the hi Rez screen,,every thing else is insignificant. Sure thinner and a bit lighter, the the upgradability of the cMBP is what sold me. I upgraded ram to 16g for $100 (OWC), and you can get even cheaper on ram with newegg and amazon. Ordered Samsung 830 256 SsD today for $189. Plus optical drive or place for second SSD or HD,
Good Luke with your decision. It took me weeks to decide!
The standard screen on the cMBP , to me any ways is amazing.