If you are located near the Waste Water Plant or San Pasqual, then you might want to tune in those sites -- but only radios who register on those sites will have traffic show up on those sites. So, if you are interested in traffic through out the city then no. Personally I have them locked out, so that my radio does not waste time trying to find the channel, failing then locking back on the main control channel.
I've test scanned the San Pasqiual Wastewater sites a fewe times, while on the ocean side by Nazarine college,a nd while up north of Eascondido and into San Marcos. I've had proper control channel lock on both areas on the alternate control channel, but even with system search, no talkgroups ever were heard at night. Maybe during the day the wastewater radios are talkign on Point Loma, but the San Pasqual site...well, unless my 700 radio was affiliated on a talkgroup, no one else seemed to be affiliating on it for my scanners.
I just run the regular 771.48125 site...I keep other site in a seperate system for scanning emergencies.