You can still keep it simple by having it billed to the 1 account and just adding a $5 or $10 based on whether it has premium or business premium. Don't really see a problem here.
Maybe. I don't know how hard/easy it is, nor do you. However, that doesn't even address the administration factor. The part that says, "Ok, this ENB customer gets 2 gigs per month & this one doesn't."
IMO, there's really nothing more to discuss here. My comment was triggered b/c a poster above seems to think ENB should be cheaper than Premium, eventhough the ENB package includes more than the Premium package.