Another good review Tom, yet people aren't listening about 4k. Some people are going to get hardware butt-hurt and or ruin their eyesight when using that resolution in such a small screen. Yes, 27" is too small for 4k, fact. Yeah you can change text size, but that defeats the purpose somewhat.
One thing I would have liked to have seen you do is what Nvidia did - have two screens of the same resolution side by side displaying the same feed - one screen G-Sync and the other not with V-sync turned off. Run a demo of something that shows a wide range of frames per second, from the low 20's to over 100. Then record this with your camera but don't upload it to youtube as they fubar it as you say; instead put the file in your downloads section for us to view offline.
Regarding the screen, as fz2011 has already asked, why does the refresh rate have to be manually selected? Sounds a bit counter-intuitive, unless the panel forsakes something else for that high frequency.
Another video where I notice Valley is artifacting - and it's not just your system! I've been testing recently and I'm getting the same, even at stock clocks. Unigine Valley is borked, whether it be drivers, SLI or that time of the month, some thing's gone awry.
