More on the 2011 iMac: I stuffed it with 20 GB RAM a while ago. It has a 1 TB spinning drive buried within. You need to remove the screen to get it out, so that ain't happening. It runs OK. Not better than you'd expect, maybe, but OK.
I did enough work on the 2011 iMac with 27-inch monitor to use it for production today. First, I REALLY miss the HD resolution that my HP laptop (and new iMacs, for that matter) offer. Once you go HD, UHD or 4K, you really can't go back. Second, I KNOW it's a 2011 computer.