One more note to add re G-SYNC optimization. Further improvement in smoothness found by ensuring that Scaling is switched on and set to Aspect Ratio using the GPU, AND checking the "override the scaling mode set by games and programs".

This of course in addition to running WOFF UE at 2560x1440 at a refresh rate of 144Hz, with V-SYNC set to half refresh rate (yielding a constant 72FPS in-game with zero tearing)