Whether to have VSync on or off is part of the tweaking process that I go through for each individual game. In general I believe in keeping VSync
off in order to promote the highest level of performance, even on games that exceed 60 FPS (on my 60 Hz monitor). On some occasions, I try to limit that FPS with AdaptiveVSync, mainly as a means of limiting GPU usage and heat on a case by case basis.
A lot of people think that FPS over your monitor's refresh rate is worthless, but I adhere to the school of thought that higher FPS means more responsive controls. So the focus is on gaming performance in terms of responsiveness, not the quality of the image on screen. Sometimes, excessive screen tearing would be a consideration we well. Again, I don't blindly choose one over the other, but I play around with the settings and tweak things for the individual circumstance.
With an Nvidia card, the ability to use Adaptive VSync makes the choice a lot easier. You don't have to worry about performance and input lag with FPS below your monitor's refresh rate. So the focus is on affecting only performance when the game is generating more than, in my case 60 FPS. With an AMD card, the choice to use regular VSync is more consequential due to the potential to: 1) Cut your FPS in half, down to 30 FPS, and/or 2) Introduce input/mouse lag. AMD users need to pay special attention to these circumstances to ensure that they are not making things worse by using VSync.
http://www.hardocp.com/article/2012/04/16/nvidia_adaptive_vsync_technology_review/#.VavqBPlVhBc