I just bought a 2015 13" MBP i5/2.7/8/256. I'd been planning to buy a refurbished 2013 or 2014 model after reading that the CPU speed upgrade in the 2015 model isn't substantial, but the faster GPU and the new trackpad intrigued me. What finally tipped the balance was when I found out that the 2015 model will drive a 4K external monitor at 60 Hz. Anyway, I'm loving it so far! It makes my 2008 15" MBP feel like a slab of concrete. I have no desire for a lighter and thinner MBA, let alone a lighterer and thinnerer 12" MacBook.