Hi Andy,
I was checking MBP with retina a week ago and was very disappointed by stability of the system. Namely, open terminal -> type top (aka unix task manager) -> try to view photos or browse not heavy websites-> watch to top in the terminal. You will see what these apps using 40-60% of CPU regardless of the actual application usage. And the screen is not that great in comparing to my lenovo w510 FHD.