It appears that the main source of latency in these tests are from key travel time, which does not accurately represent the speed of the keyboard. Gaming keyboards often has a lot of key travel before the key is triggered. This is on purpose to give better control of the key and allow for "floating" where the key is half way pressed and quickly switched between actuated and non-actuated state.

For a better test, in my opinion, the key actuation point should be determined and the timer started at that point. Of course this depends on what you want to test. But to say that a gaming keyboard is slow, just because there is more key travel, is inaccurate.

The test mentions the floating and comes to the same conclusion as i: it takes time to get to the floating position and that adds to the latency.

but this probably wouldn't feel laggy, right? because your brain is going to expect full-key-down to be the point at which text appears. especially if that point is well-expressed mechanically (eg, a click).

this would be like saying a physical kick drum or high hat is laggy, because theres a delay between when your foot starts moving and when the sound happens. (which would be silly!)

I think what you'd want here is for the tactile click to be at the actuation point. My understanding is that many or most mechanical keyboards today can't claim this.

Or maybe there is some optimal separation a key should have between the actuation point the tactile click point to account for the latency of the human's nervous system, which would do an even better job of reducing the effects of latency than if the two events were at the same point?