Partitions

My opinion is that the user roles make things too complex, and make the system prone to potential unknown issues. There are sometimes things that don't work as they should and the admin-users will complain about having to modify the app design. Too much rights could render the system unstable due to changes that are not understood, and too little would not achieve what these users want.

If you want to give the admin-user a way to disable a node, you could design multiple health monitors that the app admin can use to control the status of the nodes/pool members on the app servers themselves.