Just wanted to comment after watching your video review for this:
VESA Adaptive-Sync and AMD FreeSync are interchangeable with one another.
FreeSync is basically an AMD certification process on top of Adaptive-Sync to guarantee that everything works as intended.
There is no difference in hardware between an "Adaptive-Sync" or a "FreeSync" branded display.
G-Sync on the other-hand is a proprietary NVIDIA technology where they control the supply of hardware modules required to implement it, and they will not license it to other vendors. In other words, neither Intel nor AMD are able to support G-Sync even if they wanted to.
Since Adaptive-Sync is an official (though optional) part of the VESA DisplayPort spec now, as long as you have a GPU with a DisplayPort 1.2a or newer port, you're a driver update away from Adaptive-Sync or FreeSync displays working with NVIDIA/Intel GPUs.
I would not recommend that anyone buy a G-Sync display now.
As with all things NVIDIA, it costs more, and their aim is to lock you into their platform.
Adaptive-Sync/FreeSync does not require proprietary hardware.
While it is only currently supported on AMD cards, there is nothing preventing Intel or NVIDIA from supporting it.
I don't think that Intel/NVIDIA would be able to use the "FreeSync" branding, but FreeSync displays would still work if they add Adaptive-Sync support.
Unfortunately, NVIDIA have said that they do not currently have any plans to support the Adaptive-Sync standard.
But I think that will have changed in a year or two.
We have already seen leaked drivers which support Adaptive-Sync on certain notebooks that are using NVIDIA hardware, since it possible to implement Adaptive-Sync with the existing eDP1.4 connections that notebooks use.
And we know that it must be Adaptive-Sync, since there is no G-Sync module or other hardware inside those devices.
G-Sync displays do not have a future.
While I am sure they will be supported on NVIDIA cards for as long as DisplayPort exists, there is no reason for manufacturers to continue making G-Sync displays now, and they will never work on Intel/AMD hardware.
Though NVIDIA may be on top as far as GPU performance/efficiency is concerned right now, that could easily change. Do you want to lock yourself into one platform?
Adaptive-Sync/FreeSync is an open spec which should work with any vendor's GPUs down the line once Intel/NVIDIA release driver updates to support it.
While I don't know about Intel, I'm sure that NVIDIA will eventually.
Of course that doesn't help if you have a shiny new NVIDIA card and want to buy a display now. Personally I'd still be leaning towards buying an Adaptive-Sync display and simply treating it as a regular 144Hz monitor with the NVIDIA card until they add support for it.
I'm strongly in favour of voting with my wallet and would rather be without, than support this behaviour from NVIDIA.