mahh...its not useless @ all....in certain situations its a lot better then the plain 100 electrical combatrating. Example: in long fights when stack is at 5 and you have high critical damage ratings the dots can crit for over around 100 to 150 per procc..
in short fights its near useless. the only thing that may be interessting for DT´s is if the crits of the Dot´s are proccing VOM stacks too ? Maybe a DT can test this...?
well the dps shud be higher for conc of all classes since the proc shud activate rend, witch will give u a nice bosst... if its better then cr or offhand idk... but of all classes conc shud benefit most
remember on parsing the dps bosst from rend is not parsed under the dot but under rend