i have a 1060 i run everything in low at render scale of 100%.
So for me when enable it feels way more responsive i test it also with On and of and with low latency mode on and of in Nvidia Control panel.
SO for me the best result came in when i have Nvidia Reflex Enabled and Nvidia low latency of from control panel.
Experience on my end is more responsive and eliminating the feel of a short delay especially on heroes like Genji tracer etc. Hope this helps you