So was playing with this and you can cast, while seducing and it will not break the seduction. What you can not do is cast another channel or it breaks it. I was able to cast UA, haunt, and summon a new pet. As soon as i tried MG or drain soul it would break the CC.
It shows the seduction channel coming off my toon even when i'm not channeling it. I haven't seen anything else mentioned about this, maybe some other people want to play around with it.
I posted on official forums to see if this was a bug or not, on class forums tho so a blue will never see it.
Also just had haunt not break the cast when it did damage.