Xzulu
Mode S was very well received in the Ops room. There were some moans about some superfluous information causing excess clutter on the radar, and they got fixed immediately.
There will always be some moans when new kit etc is introduced - it's what comes naturally to an ATCO - the time ATCOs don't whinge when something new has been introduced is the time to sit up and worry.
The difference is the whinges about Mode S were done and dusted after about a week. Thereafter there were MORs put in because some airline operator were seen to be deviating from what was condered should have been the norm.