I remember trying to tell the CAA that the new ATSOCA rules were not fit for purpose at the time they were introduced. They ignored flight rules, making it more restrictive than controlled airspace in some cases.
It fell on deaf ears as in the main the ex-mil guys who now have jobs in the CAA did not care what flight rules the aircraft was under when using the old system of RIS and RAS. As in the military.
I used to use the statement in the approach section of the MATS 1 to only separate known IFR even under a RAS, so if the traffic is known VFR I would only provide traffic information, similar to class D. I would avoid other known IFR and unknown aircraft. This also meant I wanted pilots to contact me just to know their flight rules, it made things a lot easier.