I am in general against the idea, because to me, more choices means more confusion. I think there's a line between "feature-bundle" accounts and a la carte features, and the more you make incremental choices, the more you create an a la carte culture. I see a slippery slope (possibly imaginary, for the sake of disclosure) that leads eventually to

* "it will cost you 1 fbdw credit to edit this comment."
* "it will cost you 1 dw credit per day to receive tracking notifications for this thread."
* etc. ad nauseum

And then we become a facebook app called dreamville. :(