Been lamenting the pricing of GSync monitors recently, and haven't been able to find one with my preferred specs anyway. However, I've pretty much resigned myself to buying one sooner or later, and thought I might as well become "fully informed" before I finally pull the trigger.
Well... I tripped over this along the way, and if you've been living under a rock lately like I obviously have been, you might have also missed it...!
RTSS 7.2 Beta does "tearingless" VSync OFF
A few months ago, Unwinder, the author of Rivatuner Statistics Server (RTSS) added some completely new features. Its fractional frame limiter and OSD features have always been useful, but this new development is really next level brilliant. Without repeating too much of what you can read for yourself, I'll paraphrase a few of the explanations as best I can.
For those of us that still don't have either GSync or FreeSync, and the "minimal input lag & tearing free experience" that comes with them, we can at least have the next best thing.
It's now possible to run with VSync turned OFF, have RTSS cap frame-rate to the monitor's EXACT refresh rate, fix the resultant tearing line/zone to a specific location on the screen, AND then move it off-screen to the Vertical Blanking Interval (VBI) between frames, so it's never seen again.
He's also added an optional "Adaptive Sync" feature that can be toggled SEPARATELY. It can be set to work automatically, or with a user defined threshold. (edit): I tested this using the Metro Redux benchmark, because it plots its own FPS/Time chart. It functions as advertised, and I've had zero problems with it so far. (unlike Nvidia's in a couple of games.)
It's all snake oil magic and it really fucking WORKS. You need a "beefy" GPU (mainly for taxing modern games as there is some overhead), a high poll-rate mouse, and the game must be able to run in Full-Screen Exclusive mode. With the titles I've tested so far, it works flawlessly with zero artifacts/micro-stutter, and rock solid frame pacing. I've ditched all my old RTSS game profiles, as they're no longer required.
I notice the extra responsiveness even in DOOM, which has always run fast and buttery smooth for me anyway (under Vulkan). That Engine & API are works of art in my book. The biggest revelation however has been Ghost Recon Wildlands. It would never play nice with the old RTSS frame limiter, or NVidia Adaptive Sync; and because it taxes the 1080Ti to ~70% with VSync on even when idle, I wasn't sure if I would see much improvement. However, it works a treat, no stutter, and gun-play has drastically improved, especially in a firefight.
I can't believe it. This is the most exciting bit of geek gaming tech I've seen in ages, and it's free.

Beta is now up to Version 5, link on page 66:
RTSS 7.2 Beta Version 5.0
(edit): Another helpful link:
RTSS Beta 5 discussion
Added some screen-shots of my NVidia CP, RTSS, Config file settings, and the OSD stats that are available, for those who might be interested.