In the video you can see how I was switching between ASW disabled (ctrl+NUM1) and auto ASW (ctrl+NUM4)
As you can see, without ASW I get steady 90 fps most of the time.
That "performance headroom" chart is scratching along 0 and dips a bit below 0 occasionally. However, everything is butterly smooth throughout this time. I only get noticible position judder and ghosting artefacts on more drastic dips(something like 87fps).
Now having auto ASW enabled, it seems to kick in way too early and I can notice the difference immediately. it is worse than the native 89-90 mode.
In an ideal world, auto ASW kicks in at 88fps or respectively when there is true juddering.
That being said, I hope Oculus doesn't plan to force auto ASW in the next updates.
That would be bad since I optimize most graphic-settings in a way that it is scratching along that 90fps mark and it is working just fine with ATW alone.