Whether or not you're comfortable with commiting to one GPU manufacturer for (at least) the near future is something only you can answer for yourself.
However, GSync is a genuinely massive upgrade. Last Fall I went from a 1080p/60Hz LCD to a 1080P/144Hz GSync display, and quickly soon after upgraded my GTX 580 to a 980Ti. The upgrade to a GSync monitor was arguably bigger and more noticeable than the huge boost in GPU performance.
Not ever having to worry about screen-tearing or messing with Vsync/Triple Buffering was incredibly liberating. The lack of input lag was definitely noticeable. And if my framerate did ever dip below 60, it didn't become this abrupt, noticeable dive anymore. Obviously if it dips down to 49 or low 50's you might start to notice, but no longer is 59 frames a second this awful, choppy mess that it used to feel like.
Also, the jump from 60 to 144Hz was very surprising for me. Obviously this isn't something exclusive to GSync monitors, but most, if not all, GSync displays are 120/144Hz. Playing games like Overwatch at 144Hz feels incredible. I feel like I have more time to react to things, even though I literally don't. Super high framerates are far less pronounced in slower games, and you'll only be able to take advantage of them on older games or games that prioritize art over graphical prowess, but boy does it make a difference.
So I'd say it's very worth it. The price is steep, and you are locking yourself to NVidia cards, but if you're comfortable with that the results speak for themselves.
One recommendation I will make is to go for 1440p, even if your current GPU might struggle to handle it now. You'll upgrade GPU's far more frequently than you will a monitor typically, and it's likely anything you upgrade to now will be able to push 1440p games no problem. It's the only thing I regret about the display I bought is that it's 1080p.