>Worst case we're talking about an additional input latency due to vsync of maybe 1/60s? 16ms?
its generally closer to 2 frames with V-Sync [1][2]
> I don't believe 16ms is significant for non pro level eSports players and even skeptical it's a big factor at that level.
It actually is fairly significant. LTT did a series of tests with pro players in CS:GO focused on monitor refresh rate, but one test they did was 60hz/60fps vs 60hz/300fps and found that reducing the render latency drastically improved performance despite the display still being locked to 60hz.
https://youtu.be/OX31kZbAXsA?t=1911
[1] https://displaylag.com/reduce-input-lag-in-pc-games-the-defi...
[2] https://www.cse.wustl.edu/~jain/cse567-15/ftp/vsync/index.ht...