easy does it
My experience. I was on a break from flying when Southend added its D airspace. First time I flew there VFR and controller informed me about Radar Control Service I did like the sound, but didn't know if I should say something back. My instructor pointed it out right away and said it was important to read it back. So I was thinking about it later: what kind of an agreement/commitment/troubles I sign for if I acknowledge the RCS? After reading these comments I got tired, my brain overloaded and reduced to basic services. I started goofing with RCS translation:
1. ATC "Rules with Caution Service"
2. "Referee with Camera Service"
3. "Random but Clever Service"
4. "Cessna Repellant Service"
To me all VFR ATC service types come down to one formula: "help me to help you service". The difference between FIS, Basic, Traffic, Decon, Proc, RCS are in two sliders: 'help' and 'equipment'. So, FIS is practically zero on 'help' and 'equipment' required from the both sides, while RCS 'help' and 'equipment' required a lot more from both sides. Now I have to take a break from thinking.