The monitor is the one of 2 equipment which stays the longest with you during updates, the second being a PSU.
Off-topic - mostly agreed on the monitor, those live around 7-8 years with me, but PSUs are what I replace the most. Despite me buying high-end PSUs (Seasonic, be-quiet, Enermax, high-end stuff), they always appear to die/flake-out after 3-4 years 24/7 operation.
It's so bad, that if I had more uniform requirements for the PSUs across my machines, I'd keep one on stand-by. I'm still tempted to, as the last time my desktop PSU died, I could re-purpose my old server PSU, and be done with very little downtime.
In the end, with monitors it is similar though. If you're serious about low-downtime, grab an Eizo, and get 5 years free replacements delivered to your door within a couple of business days.
Otherwise, they will all age, and never mind the feature creep. At least with the old CCFL backlights, you'd get somewhat uniform aging, with LEDs and local dimming, that's only going to get worse. And the power bricks/internal PSUs could die at any moment as well.
Right now my firm recommendation would be to budget for two screens, one for work, and one for gaming, if both are needed. If gaming is your focus, I wouldn't go for the 32:9 at all, as the FOV isn't that helpful in most games. And where it is, a triple screen setup is usually more rewarding, despite the bezels. And if one screen dies, at least you have a backup to tide you over.
Regarding the original question: I guess you could try disabling GSync on your current screen, and see if you notice that? Given the additional pixels to push, you will likely drop in FPS, so if the screen can do 120Hz, you shouldn't have too much benefit from GSync, as tearing shouldn't be that much of an issue.
Or you go with the newer screen - it might be worth the added cost, depending on how sensitive you are to the artifacts. No forum post can help you on finding that out though