Appreciate the follow up, that's great work, a multi monitor aware different-Hz compositor is wonderful!
For testing web browser support -- make sure to test multiple delay values at Easter Egg'd Animation Time Graph. Edit the useragent to lie that it's a Windows based Chrome browser, so the green READY indicator appears. Wait for the graph to smoothly scroll. Now, try to make things stutter (warning: stutter detected message) such as moving mouse arrow or clicking on things. It should not have any false negatives (stutters appearing while the "READY" stays green). It should be able to accomodate up to one half refresh cycle delay (in the Insert Delay textbox) before stutters begin to appear. Chrome for Windows supports up to ~70-80% CPU consumption without stutters (e.g. number of "12" milliseconds inserted into the textbox for 60Hz refresh rate), though the test will display a High CPU Consumption alert instead of a green READY.
If you need help getting through to specific people at NVIDIA, reach out to me. I have contacts to the driver team.
We want to make sure to concurrently life all refresh rate boats, whether open source or proprietary. For example, I recently successfully convinced Microsoft to 1000Hz research (breaking 500Hz limit) -- I now have a customized Insider build capable of 1000hz refresh rate.