Yes, I have a Pentair Intellitouch system and the spa side control is connected to it. I know a pump speed had been dedicated to the spa. Two speeds were also dedicated to the pool - a slow speed when the pool is only filtering and a high speed when the pool cleaner is operating. However, I'm not sure if a speed had been dedicated to the heater. From the HL2 heater code scenario (which I covered earlier), it doesn't seem like the heater has a dedicated speed, does it? I'll have to have the repairman check this out. At the time of the high speed pump and heater failure, I did notice that the spa side switches would not operate at all (which includes the switches for the path lights, spa pump, booster pump and heater), which seems to support your statement regarding the spa side switch locking itself out when shorted.
Thanks for the input. I'll post any updates I have on the topic.