Seems that Intel developers eventually created patch that solves the main issue with Zenbook under Linux.
With Eugeni Dodonov’s patch I’m finally able to use RC6 feature and have stable system with acceptable battery lifetime. Almost two days without sudden shutdown using that patch
Happily there’s chance that this patch is going to be included in 3.3.x mainline kernel.
Beware that i915.i915_enable_rc6=1 kernel option means something different with patched and vanilla kernel.