Thanks for the info, I guess the main issue we need to be considering is PID vs On-Off controllers as well as thermocouple placement.
A PID on a march pump out of the box would likely smoke the pump cycling on off in millisecond bursts. My experience with PID's is in the heating side of process control and an electric heater does not really care if you pound it on and off all day long.
I have been reading and re-reading this HERMS Design Specifics
But I guess like all things in brewing there is good enough, more good enough, and better good enough. Its just hard to figure out what level of good enough I want to be in. I mean people have been making good beer with just a few coolers and turkey fryers, but for me the electronics side of things is more interesting than the sitting around and watching water boil...