Yes, with vsync on, in every game and on every computer.
Your testufo is very useful to determine which refresh is needed to create perfect smoothness for each individual human at each speed.
Using the testufo or moving photo 60fps@60hz vsynced, 240 pixels/s looks perfectly smooth to me. If the monitor had perfect quality, i wouldn't be able to tell it from a roll you printed the same image on and mechanically rotated smoothly in front of my face.
At 360 pixels/s, that is no longer true. It doesn't stutter in an annoying way, but it is most certainly not flawless motion. In a blind test with the monitor vs the physical roll, i could tell them apart without a doubt.
At 480 pixels/s, the effect is about the same as 360/s, just a touch worse. It is still not bothersome. I can detect it, but i could live with this.
At 600 pixels/s however, the stuttering becomes annoying @60hz. It still looks ok while tracking the movement, but it looks choppy in an annoying fashion for objects I do not currently focus on (as in, it annoys the entire peripheral vision).. Typical "real world" scenarios: You aim at something, and an enemy comes running or driving across your field of vision from the side. CHOP-CHOP-CHOP-CHOP.
You focus on a person in a movie, while the camera pans, peripheral vision goes CHOP-CHOP-CHOP-CHOP.
This is at a speed much, much slower than an actual pan in a fps game.
You always focus on something or track something, the rest is peripheral vision that makes out the vast majority of what you see at any given time.
This is easy to test using http://testufo.com/#test=photo&photo=quebec.jpg&pps=600&pursuit=0 . Just focus on the dropdown box just above the moving picture. Does the moving picture still look smooth, when not actively tracked? Probably not, but if it does, raise the speed a bit.
This is because 60fps just doesn't have enough visual information for this movement speed to look real/smooth at this speed.
Just raise the speed until the movement looks choppy in an annoying fashion. I'm certain every human can see this at some speed at 60hz. You can easily compare this to reality by holding a photo/whatever else next to the screen and moving it at the same speed.
To achieve smoothness at greater speeds, there are as far as I know two options:
1. Add artificial motion blur to mask the stutter (movies, tv, consoles (pc games optionally) usually do this). I don't want this.
2. Simply raise the refreshrate/fps.
Try this on a 120 or 144hz monitor as well, and find the limit there as well. It seems to be proportional.
It should be possible to calculate which refreshrate is the maximum needed to make the fastest object each human can track look real.
I approximate that i can't track details moving much faster than the 3840/s speed as that speed really strains me, so lets just put that as a maximum for me.
If this is proportional, then if 60hz was needed at 480 pixels/s (the level i felt was smooth, but could still tell from reality) to look smooth, then i would need 3840*60/480=480 fps/hz to feel that the fastest object i can track moves smoothly.
To not be able to tell it from reality at all, quite a bit higher (960fps).
These numbers are based on such big pixelspeed-steps that they are not really spot on, but i think they are reasonably close to the truth (lets say not more than 20-30% off).
The point is just that even synced, 30 fps is nowhere near smoooth, neither is 60fps, nor even 144fps for fast enough motion. If the framerate drops that much with gsync on during fast motion, i really think it will be easily detected as stutter (during fast motion).
If the framerate stays reasonably close i think it will work really well, and gsync in general seems like an awesome step forward.