Ok, so I am looking to purchase a MBP and would like one with a dedicated graphics card--which rules out the current low end MBPs--but I do not want to spend $2600 + tax, so I am looking to purchase a rMBP refurb or used with AppleCare. From what I have read, the 2013 revision included upgraded internals, so I would like to purchase a 2013 rMBP. My question is this, what are common issues with this model (e.g., image retention, screen scroll lag, etc.)