Knight provides you with toughness, which is what you always want to avoid in raids, unless you are playing the tank. Even in that case a whole set of Knights gear seems to be a massive overkill. You should consider only changing one or to trinkets to knights, in order to get the aggro.
I have also seen people using Commander stats on their armor, which might be another good idea, since +100% boon duration is something you are always longing for as a chronomancer in raids.