This is still low-latency territory
Even when capped out, the total-chain input lag of 40ms is still extremely low for button-to-pixels latency. This includes game engine, drivers, CPU, GPU, cable lag, not just the display itself. Consider this: Some old displays had more input lag than this, in the display alone! (Especially HDTV displays, and some older 60Hz VA monitors).
In an extreme case scenario, photodiode oscilloscope tests show that a blank Direct3D buffer (alternating white/black), shows a 2ms to 4ms latency between Direct3D Present() and the first LCD pixels illuminating at the top edge of the screen. This covers mostly cable transmission latency and pixel transition latency. Currently, all current models of ASUS/BENQ 120Hz and 144Hz monitors are capable of zero-buffered real-time scanout, resulting in sub-frame latencies (including in G-SYNC mode).
Conclusion
As even the input lag in CS:GO was solvable, I found no perceptible input lag disadvantage to G-SYNC relative to VSYNC OFF, even in older source engine games, provided the games were configured correctly (NVIDIA Control Panel configured correctly to use G-SYNC, and game configuration updated correctly). G-SYNC gives the game player a license to use higher graphics settings in the game, while keeping the gameplay smooth.
We are very glad that manufacturers are paying serious attention to strobe backlights now, ever since this has been Blur Busters raison d’être (ever since our domain name used to be
www.scanningbacklight.com in 2012, during the Arduino Scanning Backlight Project).