A good idea would be to measure the actual earth leakage on the circuits with all sockets in use. I would be interested to know the results.
I used to do a lot of IT room installs for a previous company and the local authority spec was 6 double sockets per 32A ring circuit. This was based on one workstation (one pc and one monitor) per double outlet. I always thought this was a bit on the cautious side.
that seems cautious, i might rig up a temp socket with my pc later to check