Since RMAing my defective monitor for one that seems to pull off GSync-compatibility acceptably, I'm slowly but surely warming to GSync/100 hz. Maybe it's just my eyes/brain adjusting to it, but the differences seem to be becoming larger over time compared with the 60 hz/VSync I was used to. The most dramatic game for it has to be the Witcher 3; at 65-85 fps with no VRR it seems to be a tad choppy, albeit in a fast way (if that makes sense). With VRR on, it's just smoothed right out. 75 fps+ also now feels like the new sweet spot for me, where previously I thought 60 fps was the gold standard that guaranteed smoothness.
Playing Project Cars 2 at 100-120fps felt no smoother to me than 60fps and playing the most stressful game I own, Deus Ex Mankind Divided at 1440p, Ultra settings, drops in frame rates down to the 50's & 40's still felt like 50fps and 40fps on my old monitor...certainly not the revelatory experience many made adaptive sync out to be.
Yeah I can't say I'm blown away by synced low FPS in the 40s and 50s. It's an improvement, but it's certainly noticeable the frame rate has dropped that far. I know some have said 30-40 fps became a joy to game on with GSync, but I can't say I share that sentiment. My monitor's FreeSync range means it also changes to LFC mode at 48 fps, and that transition brings flickering. It's not a huge deal if it cross over that threshold once in a blue moon, but if the game is consistently hovering around 45-52 fps, it's bad news indeed.
One thing I really like is just having a decent range for frame rate. At 60 hz VSynced the target was always 60 fps while trying to make sure it never went below that. Drops to 55 fps I usually found acceptable, but once it got to 50 fps it started getting a bit unpleasant on the eyes. Turning down settings to reduce these drops means losing image quality, and that was a tad annoying in games where 80%+ of the time the GPU was capable of running at 60 fps at higher settings. With a 100 hz monitor, those same settings mean I'm getting 75 fps+ on the same games 80%+ of the time, so GPU power isn't being wasted anymore
Borderless Windowed is certainly problematic in at least half the games I've tested with GSync on unfortunately, meaning having to switch over to exclusive full screen. I find it's been worth the trade off though. In the end it's early days still of course while getting to grips with this new technology, but things look hopeful.