Fred, you have just proved one of the points that I have been trying to make, that ATCOs are now being trained to use non-unit codes in an unknown traffic environment. They will then accept that this is the norm and my fear is that this practice will spread further.
I am fully aware of what information is provided by mode S, but one thing it does not provide is which unit is providing the aircraft with a service. A code allocated to a specific unit does this and does away with the need for "informed deduction". You know exactly who to contact if necessary. You will also retain all of the mode S information. Is it really so difficult to say "squawk xxxx"?
When I was undergoing OJT any traffic leaving controlled airspace was given a unit code before exiting so that other units were made aware of its intentions.. You had to have a very good reason for not doing so.
As I have said before I can forsee the time when any aircraft on a flight plan will be left on an ORCAM/CCAMS code whether it is inside controlled airspace or not. If every unit adopts this practice situational awareness for all units will be reduced.
You will also see that I said that ORCAM/CCAMS codes are "no better" than a 7000 squawk. This is because a 7000 code tells you that there is an aircraft there and it's level (if selected by the pilot). If you are unable to co-ordinate you need to try to avoid by 5nm/3000ft.
To a unit that is not working the traffic on an ORCAM/CCAMS code you may get more information via mode S, but it still does not tell you which unit is providing the service. Again, if you are unable to co-ordinate you need to try to avoid by 5nm/3000ft.
There are still some radar units that do not have access to mode S.