sell or upgrade Macbook pro mid-2012 non-retina

Hi, i'm have been thinking of upgrading my nrMBP mid-2012, I will be replacing my 500GB hdd with a 256GB sdd and replace 2x2GB ram with 2x8GB memory but im thinking if the graphics card (650m 512MB) can still be in good condition to play Diablo 3 :ROS, so far i'm getting fps spikes compared to D3 vanilla.

Is the upgrade the right way for me, or should I sell it and buy a new MBP with higher mem on graphics card?