I'm looking at getting a new rMBP for Logic X. Eyeing the top end 15" but it's almost the same price as the base model MP which can be upgraded to 64GB so I'm in a bit of a dilemma. RAM is probably the most useful spec for audio guys and the difference between 16GB and 64GB is colossal. I've had 16B in my MacMini before and it's no big deal. 16GB is or at least should be pretty much the default standard in any pro machine these days. I really don't feel safe/confident in buying a machine limited to 16GB however I really need that portability. Technically the MP is small enough for carry-on on the plane so it's not a bad option I guess. $3K for a 16GB limitation stings. What about a mid range 13" rMBP? Price is cut in half and it can still take 16GB. Won't be i7 though. Big performance reduction?