I sold my 15 Retina MBP (2.7 i7, 16G Ram) and will receive my rMB (1.2/512) on Monday. I'm thinking of getting a 5K iMac and have a desktop for intense work and thee rMB for portability. With the 15 I always felt like it was too heavy to carry around but definitely feel like I might need more power than the rMB can offer. I'm an architect and sometimes have to do some rending work and drawing on my computer, but not all the time. Sugestions and opinions?