Have iPad, iPhone but always had PC's. Considering shifting; however, I do a lot of DVD burning. My question is that I can get some 2011 refurbs, but they only have 4 GB of RAM. How hard is it to manually upgrade them, and is it worth it to have the internal drive? I thought about just getting the 2012 (I want a 27"with at least 8 MB) and the external drive, but the reviews of the Apple superdrive are not that good...at all. And I figure by the time I pay for the memory upgrade, I could easily buy a new one that comes with 8 MB.... Suggestions? New or old?