Interesting. I wish I'd payed more attention before.

So, wouldn't MS have included a switch in the circuit to discontinue power to the coil circuit without some kind of RPM input? I'd be rather suprised if that were the case.

Personally, I would choose something rather indirect just so there's a little more buffer between the coil and the ECM in the case of a bad field collapse... But that's just me. Plug wires do go open on occasion.