I'm inclined to believe iiyama (who presumably aren't being slung marketing $$$ by NVIDIA), as screen tearing isn't an issue I've had much problem with, and I know very few people who've complained about it of late, before Wolfenstein.
I think some people are missing the point of what this type of tech is trying to do. First of all, for some people (like me) ANY amount of tearing is not acceptable... so currently I suffer vsync lag, which is only marginally more acceptable. I am totally willing to pay a little bit extra for a smoother, lower lag experience.
Second, this tech means that you don't notice FPS dips as much - again, this is highly personal as to what is acceptable, but a lot of people who have tested this type of tech are saying that it is potentially a massive improvement. If you think, this could make the difference between needing or not needing a 2nd GPU, spending an extra £50-100 on a monitor that should last 3-4 generations of GPU, you could be saving £400+ on a 2nd GPU every gen, or getting a mid range card instead of a top end card.
This tech is not all things to all people, if you are quite happy to get a low resolution screen but with a very high refresh and then spend whatever it takes to get the GPU's to drive it to keep them locked at 144hz (or already have that setup) then no it isn't going to give you a huge improvement.
I don't know what the split is like on people who will happily spend double on GPU's compared with a little extra on a monitor that will last several GPU upgrades, or who is prepared to put up with artefacts vs those that don't, all I can say is that *I* would like a 4K Gsync monitor, so this thread is of interest to me and info on this monitor is of interest.
I don't really understand why you feel the need to go in to every Gsync thread and keep changing your mind between bigging up AMD's version (on the basis that you think it is "open" despite AMD saying it uses "secret sauce" that only exists in the very latest AMD cards), or saying that this type of tech is pointless... for someone who seems to now think that any of this type of tech is pointless you seem to go out of your way to force this opinion on other people.