I think you are confusing input lag with pixel response. If this actually is VA there's no doubt average G2G is going to be well north of the claimed 5ms which is at the max OD setting (faster).
Also this is a Gsync panel with no additional scaler so input lag will be in the 5ms range or less.
I think the impression of input latency is greatly affected by refresh rate. A 144hz panel is going to feel snappier then a 100hz one. How many people can tell the difference between 5ms (Dell) and 15ms (Samsung). I sure as hell can't but definitely notice the difference between 100hz and 144hz.