I initially thought 3d game frame rates shared the limit that film exhibits, i.e., 30 'percievable' frames per second. But, a game tester friend of mine said he learned at work that, for technical reasons unknown to him as well, in 3d games the percievable range of fps is more around the 90 fps mark.
So can we 'see' 90fps in games. Yes. Can we see more than that? That point is debatable.
But its all about smoothness. At high frame rates, e.g., over 60 fps, quality is much more important for smoothness then quantity.
I have tested just about every mode, and vsync on is undoubtedly better/smoother than having it off.
If your monitor is refreshing and drawing a new frame with each refresh (i.e. simultaneously) then it will look almost cinematic. My iiyama 450 pro, refresh set at 100, maxfps set at 100, is perfectly smooth. In contrast, i used to play with vsync off, for more frames, but very very choppy compared to synced perfection. And if we cant percieve more then 90, i think 100 of synced frames, constant, unwavering frames is just right.