Hi, I own a MBP 15" i7 quad core late 2011. It has got 8GB RAM and I added an extra SSD to replace my optical drive. So it now has got an SSD and a SATA, which is a very good combination now. Because the logic board has been broken due to the GPU failure, I have to pay more than $700 to replace it. Since many people is encountering the same problem and apple refuses to acknowledge the issue, they won't repair it under warranty. For that, I'm afraid that after the replacement the failure would accur again because I already replaced the logic board last year. So, maybe I was thinking of buying the rMBP 15" but it costs a lot of money, approx $2600. How much difference will this rMBP perform compared to my model? I'm not willing to pay so much money for a marginal extra performance. Retina is cool but not necessary.