I read on the main site that LightBoost is actually better than G-Sync if you can keep a solid 120 FPS. What if you can pull a solid 200 FPS constantly with LightBoost enabled? Is there any evidence that LightBoost does not have an benefit from this? Should you actually lock your games FPS to exactly 120? Why?
The problem with LightBoost is if any part of the screen remains the same for two refreshes, you'll get a double-vision effect when following motion. This is visible on CRTs as well. As long as the frame rate is at least 120 FPS, there won't be a problem.
If you want the smoothest motion without tearing, use vsync to synchronize the frame rate with the refresh rate, but that will add some lag.
With vsync off, you should not lock the frame rate to the refresh rate because that will make tearing worse, despite conventional wisdom. You want the frame rate to be as high as possible to improve responsiveness and reduce visible tearing.
Oh, so have the FPS completely unlocked with Vsync off and LightBoost enabled?
Yep. And if your framerate is dipping below 120fps, dial back the visual settings (or, like, by more GPUs)