Hi, Given my budget, I have determined that I can either get the 13" retina MBP with i7 CPU upgrade, or 15" non-retina MBP w/ 8 GB of RAM. Basically, it boils down to dual core with SSD, or quad core and discrete graphics with hard drive. I don't do image/video editing or gaming. I am a physics grad student who runs Mathematica code for my research. It's not all that heavy-duty -- my longest codes take 15-30 minutes to run, and those are rare. Other than that, word processing, web browsing, and creating keynote presentations. I carry my computer around occasionally, but it spends most of its time on my desk or in my living room. I am leaning towards the rMBP. Will the quad core/GPU speed increases from the 15" non-retina be enough to offset the faster SSD and the 2 pounds of weight savings?