I'm considering two Mac desktop configurations and I'd appreciate some advice. How do these two machines compare with regard to speed and power? I know these are relative terms, but just generally, bearing in mind I'll use the preferred machine for pretty intensive Photoshop work: 1. Mid-2011 iMac 3.4 GHz Intel Core i7 quad-core, AMD Radeon HD 6970M 2GB VRAM, and fitted with 16GB RAM. 2. The current (April 2014) 15-inch MacBook Pro with Retina display 2.6GHz Quad-core Intel Core i7 with 1TB PCIe-based Flash Storage, NVIDIA GeForce GT 750M with 2GB VRAM, fitted with the standard 16GB RAM - used with some external display (undecided as to which one). Also, if the rMBP is preferable, is there likely to be an update to the rMBP soon that would make waiting worth while? Thanks!