I need most of the memory I can get running VMs and 16GB can sometimes be a squeeze. What happens if you switch on the discrete graphics chip in the MBP? Does that mean that the shared main memory used by the integrated graphics is given back? Waiting for my maxed out MBP to arrive but wondering if I would have been better off with base spec with 16GB + 1TB. Not convinced the processor difference between base and 2.6 is all that much in reality.