My sister has an iMac purchased in 2012 (Mid 2011 model, I presume) and equipped with Lion (10.7.5). It is a 21", 2.5GHz i5, 4 GB RAM. The Apple History website (http://apple-history.com/iMac) lists the max OS for that model as 10.10.4. However, they also say the same for my early-2013 15" MacBook Pro Retina (16GB, 512GB flash). I wonder if they simply haven't updated that site for 10.11.x. Any reason to believe that 10.11.3 won't run well on her iMac? It also seems that there are a lot of one-star reviews on the App Store. Should she stick with Lion? I'm still on Yosemite on my MBP so I have no experience with El Capitan.
