After revisiting the TechEdge spec, I doubt we'll add anymore TechEdge PID's. You see, the RPM PID is scaled in such a way that the user would have to manually configure it anyways before it would be useful. And since that information is available through the OBD-II port, it doesn't make too much sense to add it.
I see what you mean about RPM. But the other 3 PID's are usefull (thermocouple inputs, also convertable to 0-4.99V inputs).
Regarding scaling, wouldn't one have to do manual configurations for any of these types of PID's coming for AUX devices?