NEWS:
When I start the game in full screen I have this problem, but if I go to the desktop and return to the game (alt + tab), the vsync starts to function properly, starting the game directly in the window mode the vsync works properly from the start, I believe that the problem is in fullscreen with windows 8, because I noticed that in full screen changes the maximum frequency, this also happens in other games, rather than 60hz recognizes 59.94Hz, I think the problem start from this situation, I am aware that on windows 7 this does not happen, I do not know if it is a problem of windows 8 or by AMD drivers, or if for some reason it is rightly so. But I think you should find a permanent solution.

Set game in "Full screen windows" and the game start with vsync working properly, it is a temporary solution.

So there is hope that V sync would not anymore cutting frames??

But..i think (not entirely sure) that V sync affects mouse lag too..

update: I have the same problem with windows 7 and geforce 550ti

video here:
http://www.youtube.com/watch?v=KOy-8cwtj54

I have screen tearing at any FPS using a GTX 670 that occurs even when FPS is below the monitors refresh rate. Strange.

http://feedback.arma3.com/view.php?id=3535

finally having solved the problem of compatibility between steam - sweetfx - msi afterburner and radenpro I managed to get them to get along with the correct parameters, now I did some testing with the with RadeonPro, if in game is enabled the vsync and enabled the option you see in the image below that resolves the problem of vsync, and it working properly since the first start in fullscreen mode, I think you should analyze how an external program fix the problem by integrating the solution directly in the game.

http://img90.imageshack.us/img90/410/8ano.jpg

second video:
http://www.youtube.com/watch?v=vp8BSrURxlE&feature=em-upload_owner