Yes it will work for the San Diego Sheriffs Department, which is on the San Diego Regional Communications System (RCS). How long the scanner will last depends on if an entirely new type of radio technology is employed sometime in the future. The next change is likely to be an even narrower "narrow band." The PSR-500 is capable of a channel spacing of 6.25 kHz. This is something the PRO-96 will not do.
If a department starts using encryption, or Open Sky, or similar technologies any scanner will not work for those systems and most likely never will. I don't see that happening very soon for the RCS as the system is huge and the cost would be very high.
The PRO-96 is best programmed with computer software. Programming via the keypad on the scanner is quite difficult considering the scanner has a 5,000 channel capacity (10 V Files of 500 channels each). The PSR-500 has 20 V Files with an "object capacity" of 1800 plus for each file. An object is a conventional frequency, a trunked system (all the trunked channels in a trunked system is one system and one object), a talkgroup, a limit search, and a signal sweeper search. With that capacity a computer is definately needed. I recommend Starrsoft Software for the PSR radios and the PRO-96. Don Starr puts out a very good product.