The Adaptive Sync is my main issue as well. I've got a 980ti as my main card, because only in Pretend Land was I buying a 4GB graphics card (Fury range). I would like an adaptive sync monitor because hell no am I buying into G-Sync. nVidia need to pull their head out of their arse and support adaptive sync.
I'm looking to get new monitors in the near future, and Adaptive Sync is really why I want Vega to be competitive. Even if I "have" to buy another nVidia card, I still not going for a G-Sync monitor. I hate the concept of vendor specific features like that. I'd sooner go without any sync as it's more likely I'd change graphics cards before monitors anyway.
I'm currently on a 980Ti myself, and on a FreeSync monitor. It's in there since my Fury X died, and before that I had SLI 980Ti with the ROG Swift G-Sync monitor.
Adaptive Sync really is wonderful; and honestly my friends, and I have not been able to tell a difference between Fury X FreeSync, and 980Ti G-Sync.
I agree about vendor lock in; it's horribly annoying; which is the reason I bought 144Hz monitors. Even without Adaptive Sync they're a league ahead of normal 60Hz ones; and the Adaptive Sync is the cherry on the top.
I hope Vega lives up to my needs and expectations at least as it'll be an instant buy for me; and already owning a FreeSync monitor for gaming is still a plus then.
In the end, all anyone really has is speculation, and estimations. We'll have to wait until Computex to hear anything about consumer gaming Vega cards.
AMD's main issue still seems to be the failings of their partners here. If SK Hynix managed to roll out 2.0Gbps, or even quantities of 1.6Gbps 4GB HBM2 in Q3 2016 like promised we'd all have Vega by now I suspect.
So even if the only Vega card was 10% faster than the GTX 1080 at best, everyone would be happy.
Instead we're moving towards Q3 2017, and SK Hynix have no listed 2.0Gbps 4GB modules, never mind the imaginary 8GB modules; and what looks like limited supply of the slower 1.6Gbps ones; which AMD seem to be running at 1.88Gbps on the Vega Frontier Edition to try and make up the bandwidth issue.
Since then NVIDIA also launched the new Titan Xp, and GTX 1080Ti, so now people expect 1080Ti performance at a minimum because of all the delays. :/