>>713915193>>713914508G-Sync/freesync fix the problem of vsync only operating on "halves" where 120Hz with a dropped frame becomes 60, then 30, then 15... By presenting the frames as they arrive even if it's late, it creates a much smoother experience.
However you should NOT be "locking your FPS to 5/10 below to keep it engaged." That's crazy talk cargo cult nonsense. The only time you should be messing with framerate caps is because your GPU is making too much noise doing 300fps and you don't like the driver's method of reducing GPU usage. Or if the game you're playing is programmed like trash and the physics breaks at high FPS or something.
You don't WANT g-sync engaged more than it has to, but you DO want it to work when it needs to.