Just to clarify something about channeled spells. Each channel tick has its own individual chance to be either resisted, hit normally, or crit. It isn't like you cast a channeled spell and if it does damage the first time it will do damage every time till the channel goes away, that isnt how it works (people in other threads didnt understand that so im clarifying).
My proof :

Spells that deal channeled damage like arcane missiles and blizzard each hit targets multiple times during the spells channeling which should be procing clearcast.
The whole argument really comes down to if you have higher than elementary school reading comprehension skills or not.