I work as an ATCO on several airspace sectors at Scottish Centre.
Believe me, the screens are cluttered enough at the moment especially when trying to distinguish 'your own' traffic at say FL100+ from low level VFRs or helicopters.
On a 16 inch monitor on 250 mile sector, it does not take a rocket scientist to work out that the SSR labels on each aircraft can be 15 miles across.
Well seen the dire state of the UK Air and Space Industry as there are obviously no rocket scientists within the CAA.
<rant on>
IMHO there are too many deskbound pen pushers who have never tried to..
a)separate aircraft for a living using the rules THEY create
b)operate an aircraft in the crazy overtaxed and over-regulated UK environment
c)use the crap equipment at Scottish Centre
d)understand that not everyone actually needs to be 'controlled' - (we don't all have to be identified VFR actually works quite well.)
e)understand the needs and rightful freedoms of GA
f)think how badly cluttered radars will become if EVERYONE puts up a Mode S response.
g)think that while Mode S is a good idea in a Class A TMA environment, it is not appropriate to burden users in Class G airpspace.
h)think that it won't work below radar/radio cover in mountains and valleys
i)won't solve the real 'collision' issue of military aircraft without TCAS
Just my £5 worth
<rant off>