I was looking at the 2011 iMac 21.5" 2.8GHz i7, ATI 6770M GC with 512mb memory but have seen some refurbished iMac 27" 2.93GHz i7, ATI HD5750 GC with 1GB memory on the apple site for a similar price. The iMac would mostly be used for photo editing/graphic work (photoshop & lightroom) and cad (highdesign & sketchup). Would there be any benefit in going with the older model because of the increased vram?