I am thinking about changing my 2011 MBP for a 15inch Retina, possibly refurb or used, but want as much storage as possible. If I buy say a 512 Gb model, how easy is it to upgrade the storage using the OWC offerings or other ? Buying a 1Tb model adds a lot to the price, and cuts out refurb and used options. I have found this article which makes it sound quite easy. (I am quite experienced working inside MBPs) I can't find any posts here from anyone who has actually done this? Any poo-traps? or advice? PS I know increasing RAM is definitely not possible so will definitely get a 16Gb model.