I bought a used iMac off eBay a couple weeks ago, an early 2008 20" 2.4GHz model. It came with 2GB of RAM and a bad HDD. Before it arrived I ordered 4GB of RAM (2x2GB, didn't check that I could go 6GB before ordering), the suction cups, the torx set and a Sandisk SSD Pro. When the iMac arrived I immediately installed the memory then the SSD. Then I ran into my first problem, I didn't have Lion associated with my Apple ID so I had to purchase that and wait a day for activation. Once that was done I installed Lion and then upgraded to El Capitan even though I wanted Mavericks (couldn't get it from the store anymore). I decided to buy a USB thumb drive with the installer on it from Amazon and it arrived yestereday. Installed Mavericks and I have to say it seems to function way faster than El Capitan. Programs open faster, transistions are smoother. Just an overall better experience. I haven't done any benchmarks, this is all just a general feeling I get when using it. Please Apple, don't stop support for Mavericks any time soon, I am loving this version!