I'm buying a used macbook pro off craigslist, but was wondering if there are any years to avoid? not interested at the moment in going back past 2008, so 2008, 2009, 2010 (not too many available 2011s right now). I'll be upgrading the system RAM (max), 2 internal hard drives (SSD) with optibay so not too concerned about those items. Really just wondering about the year so I can have enough processor power as well as ensuring the USB works with Audio 6. Any thoughts?