I highly doubt anyone notices 1ms latency. I might believe rare people can notice 10ms.

Anecdotically, 7ms vs 3ms latency is felt as weirdly heavy action when playing midi keyboard. It's not felt as latency, but it's felt. And I bet the difference could be reliably established in double-blind testing (3 samples, find an outlier).

1ms seems less believable, but I wouldn't be surprised, if some people could notice that too.

Again I have to point to this Microsoft Research Video.

https://www.youtube.com/watch?v=vOvQCPLkPt4