Don't know if this has already been adressed, if so I apologize for bringing it up again.
My opinion on disrupt(and all form of defense really) is that utility/CC abilities should not be defendable. HOWEVER, this might be troublesome if implemented in a game such as warhammer, with a big focus on hold the line in largescale fights.
My philosophy is that: less random element is always better, and as it stands now it's way too much random going on with every class(some getting hit harder than others). A failed selfpunt, root, knockdown etc can easily mean the difference between a win and loss, and without really any skill involved since it's just luck.
Damage abilities however I can understand having mechanics for avoid as a way to mitigate damage, even if I would prefer just flat decreasing the damage output instead(this wont work in war though considering the math behind the damage calculations and how integral part of the game avoidance is).
I do however feel that dots should not be disruptable twice, explanation below:
ab 1, fireball 3s cast 1000 dmg
ab 2, dot 9 sec duration 1000 dmg
Lets say the enemy we are hitting has 20% disrupt, this means that the overall damage of both the fireball and the dot would be 800. The problem with that is that the dot actually calculates its disrupt twice, once on application and once on tics, which gives it a bigger damage reduction than the fireball gets. This "double disrupt" gets exponentially better the higher disrupt the defender has, which is also a problem with regards to balancing dots since it's not a linear curve as is the case with a single disruptcheck.
A possible problem with removing the initial avoid on dots is in the case of rotten arrer, where having an undefendable HD might be a tad too strong. Instead you could remove the dirsupt of the tics, which might be a better solution for this exact reason.
Sorry for the long rambling, im just passionate about math and stuff