This question is for the guys. Which CIM do you prefer?
I'm asking this because guys have different reasons for enjoying this. I can see the argument how both are visually appealing and depending on the woman and her approach it can be a very memorable experience.
The open mouth is very porno like. In a way some guys can see it a bit "too slutty" or borderline demeaning. Guys however like that. The closed mouth can come off very flattering as it gives the appearance that she wants to get every last drop from you.
Preferably I'd like a closed mouth cim but twice there's been instances where the sensitivity level when I'm cumming didn't cause for a great feeling on my head area upon the application of a woman's warm mouth.
Despite that, I think I'd still go with closed mouth CIM b/c it has more of an intimate feel to it.