does anyone use subwoofers in their setup?

[Stigmater]

You need to apply the delay to the fronts, not the sub (assuming your sub is near to your fronts/mains). It's the sub and any DSP in and/or in front of it that "lags".

A stepless phase control really would be best. During setup in my system I've noticed there's a real small "window" where things are optimal, just the tiniest change of the dial would again result in an out of phase setting again. (it's a bit like tuning to a radio station)

Stepless phase controll indeed best , i found that on 80Hz sample i found very smal window around 40" on SW
and exactly as Antoine mentioned , tiniest change would result in an out of phase, not in a million years i would find that spot with out trick from sounddoctor.

 
I personally didn't liked the sound when Speakers and SW set on 80Hz as recommended by sounddoctor ( Speakers Hi pass 80 Hz, SW low Pass 80Hz)
So if after setting the correct phase by playing 80Hz sample i changing the setting in Devialet back to Full range speakers and 35Hz low pass on SW,
does phase that i set earlier is correct now for new settings as well (35Hz low pass on SW)?

if so , what delay i need to apply if my SW is in the left corner next to my left speaker along the wall 3.5m away from my listening position ?
The delay i should apply on speakers or on SW ? (According to my understanding its on speakers)