Lot of misconceptions here, 1280x720 at 60fps is less pixels per second then 1920x1080 at 30fps. (88.9% to be exact) So the graphics would be the same, they could even be a bit more detailed at 720p60
The clarity of the picture will be better at 1080p30, no unnecessary blur and lag from upscaling to the resolution of the display.
Switching to the displays native resolution on pc always seems like peeling of a layer of plastic from the screen. 1080p all the way. Stable 30fps should be possible next gen, I rather have that then screen tearing at 60fps.







