I'm debating between a Thunderbolt Display for my rMBP, or a 2011 27" iMac. The iMac can be used just like a TBD, and is roughly the same price refurbished. My rMBP covers most of my needs, but a desktop would be nice to have again. My only worry is that buying a model that's three years old might be a bad idea. Though I could, and likely would shortly after buying, upgrade the RAM to 16GB. I'd likely use it for 2-3 years, then worry about upgrading both the rMBP and iMac and selling these two. At $1100, is a 2011 iMac still a good buy, or is a newer model the better option? Or would I be best off sticking with my rMBP and a TBD?