I'm considering getting a new 5k iMac but the thing that concerns me is how my Blizz games will look and run on the machine. I won't even attempt to run them in 4k as I'm sure framerates wound be awful. My question for current owners is how do the games look running at 2560x1440 on the 5K iMac? Is there any blurring or visual muddiness due to the up scaling? Thanks for the help in advance.