Yes, you'll be perfectly fine. you can always turn down a few settings if you're hitting an undesirable frame rate, but that's what G-Sync is for!
It makes frame rates which may appear very juttery normally buttery smooth, and improves your experience by a mile.
30-70fps is the target area for G-Sync to operate, meaning it is meant to allow you to turn up settings to higher quality while still achieving a great gaming experience.
You have nothing to worry about, it gives you a better experience and also futureproofs you.
The monitor is a great deal, and is the best choice for your use in my opinion.