I've never worked for Rural-Metro, but I've gone down to check out their operation and had a chance to talk to some of their medics. My impression is that they have a very good operation, much better than AMR Riverside where I used to work. Most of the units are stationed at fire stations, and you run calls with the engine, which has a fire medic. Some years ago the FD got rid of all their medic ambulances, and now Rural-Metro does all their transports for them. Pay is a little better than AMR, but not much.
I talked to a guy who worked for AMR in Chula Vista, and he said the pay was horrible. The only positive thing was that they worked dual medic and that fire was BLS only.
Protocols for San Diego and Riverside are similar (much better than LA), but in San Diego you are required to make a very lengthy radio report to the base.