A bit of a necro here, sorry.
I've been using a G-Sync display for about a month. I can certainly tell the difference in smoothness and response time when the framerate is closer to 60, as it was with my old monitor. Even if it is something you don't directly notice an improvement, the fact that you're not noticing anything annoying says something, too.
But yeah, G-Sync should be controlled via the Nvidia driver and the G-Sync module in the monitor. It doesn't need software support. I was a tad confused when I saw the free sync option upon launching Ashes, as well.