The GP850 uses the same second gen LG panel as the S2721DGF OC'd to 180hz. If you find the S2721DGF washed out I really don't know what to suggest it's a Wide gamut panel with no clamp which means if anything you should find it overly colourful on sRGB content.
The S2721DGF actually follows the sRGB gamma curve better than most monitors out of the box, at least gaming displays, similar to the AW2721D. Thing is unless you buy something that is pre calibrated to a low dE there's going to be inconsistencies. My S2721DGF actually measures better out of the box than my AW2721D. The GP850 doesn't have good calibration at all it's actually fairly average for a gaming display and way off curves in comparison although it does have a less than 3.0 in the sRGB mode with a clamped gamut in the measurements posted so far but it varies.
If you're worried about colour consistency you need a colorimeter or buy a premium display that guarantees a less than 2.0 out of the box.