Larry, my PA-30 had an old set of GEM analyzers that were marginally helpful at best. Many of the probes were burned out too. Because my panel was already cut for two seperate instruments I went with EI UBG-16 analyzers. The electronics are not as sophisticated as JPI, but very reliable and accurate.
I just completed the first flight since getting the new monitors installed and I'm so happy to know whats really going on with my engines. Since I have turbos I added TIT probes and oil temp also. I now know that I have nice mixture distribution on all cylinders, very acceptable CHT's except cylinder #3, and I can accurately lean for climb, cruise, and decent.
In my opinion a good analyzer should be a requirement on all turbocharged engines and are certainly a very good idea for all injected engines. They make diagnosis of plugged injectors and plugs a breeze. Just tons of information about the health of my engines that make me feel more comfortable flying behind them.