I am considering a 2015 15" Model:Z0RF-MJLQ27 - is this the most powerful 15" 2015 Model maybe still available? Looking at the specs, I am a bit confused by the Graphic Card description in the specs? One website says: Intel Iris Pro Graphics with 128 MB and another says 2GB - so which is it? Is the Intel Iris Pro the best choice? (it appears to be the only option for the 2.8 GHz which I guess is the fastest CPU)?