Well, last hour of the raid went into Omnotron, best try was 65%. Getting gripped into a cloud on top of the adds was one of the main killers, along with people stacking up on lightning conductor before it changes to shadow conductor. A few other things, essentially boiling down to people failing. A few more hours of tries and it should fall.
The thing that really caught me off-guard the most is how fast the golems switch. Not a moment's rest for the whole duration of the fight.