[Shine]

"Missed vsync" means: shitty and utterly broken driver - can you turn off AERO?

Next time I'm talking to an Intel rep, I'll tell him "your drivers are shitty and utterly broken." NOT. This used to work perfectly, but I don't remember at which point (read: which XBMC rev.) it stopped working. It's a Kodi issue, not a driver issue and I was actually planning to look into it before Helix release, but lacking the time, unfortunately. So I was hoping that any of the Isengard changes (e.g. afedchin's DX11 update) fixes it as a side effect.
As for turning off Aero, I can try and report - didn't think of that. Update: No change when disabling Aero.
Note that earlier builds did not show the "missed vsync" issue with Aero enabled or disabled, no matter. Again, talking about my box(es) only, as I understand that others were seeing the "missed" counter in action across all XBMC versions.

Also make sure "Sync Playback to Display" only makes sense with "Resample Audio" _and_ passthrough completely disabled.

I assume you mean "resample only works with passthrough disabled". Correct, did I say otherwise? As far as I could read from the PRs, this has finally been fixed in Isengard, ie. Isengard won't allow users to enable passthrough and resample at the same time. This is offtopic, though, since with passthrough enabled, Helix will just ignore the "sync to display" setting, causing stutter but not a/v desync, iirc.