Hi, I'm in the need for more GPU performance from my Mac. I currently have a 13" 2012 MacBook Pro 2.5Ghz i5 with an HD4000. Someone is offering me a 2.8 8 core Mac Pro 3,1 in trade. (4GB Ram, AMD 6570 2GB GPU) with no hard drive (but I'd be installing my own SSD). I'm really tempted as I could in time upgrade the GPU and I'm more in need of a work station for my iOS development. However a couple of things are putting me off, mainly the fact that the RAM is ridiculously expensive and the 3,1 model is getting a bit long in the tooth and I'm concerned about future OS X compatibility. I know that in benchmarks the 3,1 blows my i5 out of the water but does it really in real life? Will I be taking a huge step backwards?