When coming to crit hits you must look very carefully on yours and opponent's buffs. DS toons under SLKR can't be critically hit while they have Advantage buff. They are also regain Advantage every time when it's dispelled without actually causing crit if they don't have buff immunity.
So, if you are attacking enemy while they have Advantage you won't crit, unless the Advantage is dispelled right before the strike (SLKR stun or Hux mass assist). Also Kylo's AOE dispels debuffs and regain Advantage to every toon, so it's very good defensive maneuver and must be used timely in mirror matches, instead of blind "it's off cooldown, lets hit". Especially when it's comes to 1vs1 mirrors which such matches often end - protecting from enemy crits may be cruicial there.
P.S. But I also don't like SLKR mirrors. :)