If there is no holdover time established, then maybe you shouldn't go flying. I understand that precip type, intensity etc., is variable, and subject to a range of interpretation, however, I may hesitate to take off lacking positive guidance from the holdover table. PIC judgement is a big piece of the equation, however.
Come to think of it, I don't believe I'd recognize a snow or ice pellet. Anyone in colder climates have experience with this type of precip? I think that lack of experience and perspective in the "lower-48" may be driving the new AC's.
My employer is working on updating company policy regarding operations in ice pellets, presumably in responce to the AC.