We don't know that group owners will be informed in any way by GIO if a member of their group is a paid GIO account holder or not. Everyone seems to be assuming that group owners and members will be able to somehow figure it out. This isn't necessarily true.
Just as no one knows which groups are paying groups and which groups do not pay, the same applies to GIO account holders. No one, except GIO management and the account holder needs to know.
Here's how that would work:
A Basic tier group has 104 members. Someone applies. The owner accepts them. Nothing requires the owner to know if the new member is a paid account holder or a free account holder. The owner has no need to know which members are paid account holders and which aren't. The owner just knows they have approved a new member. There is no reason for the owner to know anything other than they have 22 "free" (available) slots and can invite 22 people to join. Or not.
Let's say, time goes by and that same basic tier owner now has 35 slots. Yet they still have 105 members. What happened? Well some of the members decided to get a paid GIO account. Which means more free slots have been released back to the group from GIO.
Now it's a week later and that same owner logs in and sees there are 16 available slots. They still have 105 members. What happened? Some members opted to return to a non paid (free) GIO account. The group owner doesn't need to know which members converted. All the owner needs to know is he/she can send invitations to 16 people to join the group.
On the GIO side of things, if a member opted not to retain their paid account, GIO would notify them that they will be removed from groups X,Y, Z because those groups are over their capped limit. No disgruntlement between members and group owners. The communication is soley between GIO and the account holder. The account holder deals with the consequences of not renewing their paid membership. Just like any other member that leaves a group, the owner need not know why they left. The member can request at a later time to rejoin.
In other words the 100 slots of a capped basic tier group are on the GIO side of things and not the owner side of things. If the owner has zero slots, they can upgrade to Premium, essentially "buying" 300 more slots from GIO and the ability to direct add members and have more features.
For a Premium owner their concern is direct adding. They start a group with 399 available slots. As the group fills, those slots decrease. But the Premium group owner will not know which are filled by paid account owners and which are filled by free members. The group owner's concern is how many slots are left to direct add members. Regardless of whether or not Samuels proposal is implemented, the owner is only looking at how many vacant slots are available for direct adding and for sending invitations.
Now suppose someone with a free basic account applied to join a basic group with 100 members. Their request is denied by GIO system letting them know their application was unsuccessful because the group is full. (ThIs will happen after Jan 18 regardless of whether or Samuels Proposal will be implemented).
Ditto for a Premium group with 400 members who does not want to pay the additional per member charge. The owner need not be made aware of who in their group holds a paid or unpaid GIO membership. Their concern remains focused on the number of unfilled slots that can be filled if they choose to fill them.
If Samuels proposal goes through, GIO will need to manage the back end of requests to join capped groups. GIO will need to manage account holders moving between free and paid accounts. GIO will need to decide if there is a need to inform group owners, whether or not they have paid account holders in their groups.