Has anyone tried the reaction time test on this game? Seems a lot more consistent and reliable than humanbenchmark since you can set it to 500fps and exclusive-fullscreen to minimize the latency

As Comanglia already mentioned most of the important points, I'd just like to add that disabling vsync (windows aero) makes a pretty big difference (assuming you are on windows7 or lower). On Windows10 you cannot turn it off, therefore you are always in a disadvantage in this test. In addition to turning off vsync, you could set your browser's framerate to above of your monitor to make it so its refresh rate is not (as much of) a limiting factor anymore, in theory anyway... I have no idea if the test itself has a maximum update interval/framerate which would make this pointless.

Hardware acceleration can work either in favor or against you, it depends on your setup. Just try it and see what seems to work better.

The percentiles shown on the site are essentially meaningless nowadays, so don't make any assumptions based on that. The true latency corrected averages might be around 185-205ms however, if you need a starting point.