I hardly even notice difference between 30FPS and 60FPS. Someone showed me the blue small cube bouncing around with 15, 30 and 60 FPS the difference was clear with 15 and 30, but 30 and 60? Not so much.
EDIT: here it is:
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I see the difference but it doesn't bother me at all. 30 FPS is fine for me and I wouldn't want a developer to stick time in some more frames then polish up the graphics.