It looks to us like ViewSonic is hedging its bets with the XG2700-4K. Since the panel is of such high quality, there's no reason why it can't serve multiple purposes. On one hand it's a high-res gaming monitor with FreeSync. Even though it doesn't offer a refresh rate beyond 60Hz, it still puts smooth motion on the screen with reasonably low motion blur and tolerable input lag.
On the other hand, it's a professional monitor with a factory-certified calibration. If you don't require a wide-gamut option it's the most accurate display we've ever tested in the sRGB colorspace. With no adjustments whatsoever it beat most of the expensive pro screens in our database for grayscale and color accuracy. After calibration, it sits firmly on the top of the heap in those same categories. It's only in the gamma test where we found a tiny flaw. And relative to other gaming monitors, that's a non-issue.
So if you're looking for a professional monitor that is decent for gaming, we think the XG2700-4K is pretty hard to beat. But if you're in need of a great gaming screen that also has accurate color, you'll have to consider the limitations forced upon it by Ultra HD resolution.
Even though we'll have sufficiently robust interface standards eventually, there are no monitors that can currently accept Ultra HD over a single cable at refresh rates above 60Hz. Adaptive sync takes care of some of the artifacts associated with that but the XG2700-4K has a lower FreeSync limit of 40Hz. That might be an issue for those with less powerful graphics hardware. If you're gaming prowess requires the absolute lowest possible input lag, you're probably better off looking at a 144Hz product; there are more and more available in the QHD category. And IPS panels are finally becoming a factor in the gaming world.
To the more casual entertainment-seeker however, we think the XG2700-4K represents a pinnacle of color accuracy, quality and video performance. Our gaming experiences were extremely enjoyable once we dialed in the right balance of detail and framerate. FreeSync kept the action tear-free and smooth and we loved the deep contrast and vibrant color delivered by this exceptional display.
In our tests the ViewSonic set several top or near-top records for contrast, grayscale and color accuracy. That these results can be achieved without calibration is impressive; and even more so when you consider the low price tag.
As one of the most accurate monitors we've ever tested, coupled with decent gaming cred, we're giving the ViewSonic XG2700-4K our Tom's Hardware Editors' Choice Award.