We moved to the new pricing, and found that it works differently from the old one:
In an old one, if we create a user group with permissions lower than those of Developer, each user in such group was still billed for $9.
New pricing has a user group Commenters, and we're not billed for the users we add to this group. However, if we create a user group with LESS permissions than commenters - for example, without viewing permissions on certain module - we're billed for this as a Tester.

I think this part of billing should worked as it worked in an old pricing plan.