Very odd. The coil is alway hot until grounded if I recall. And its only 12v that is grounded by the ECU. To have a specific coil go bad could indicate an ECU issue or you are using aftermarket coils. Only go OEM. I would take a used OEM over a new aftermarket any day. With all that said, I can not see how its RPM related, even more strange.
Both aftermarket and OEM coils blow. ECU... that's an idea. I'm thinking maybe the wires where I can't see them or some sort of module, but have no idea what. Maybe I'll see about replacing the wires and see what happens.
You could disconnect the ECU and test the wires. I would not do so with the ECU connected. The coils are in pairs, which is even the stranger part since you have an issue with one and not two. Two coils alway fire at the same time, hence the "wasted" spark system. Its for emissions.
edit: Oh, crazy thought but maybe replace its companion coil. Maybe the companion is the actual issue. Just a wild guess but at this point...
As for companions, I think the order is:
Just throwing out ideas out hear but could the ressistance of the path through plug be to high. Google seems to indicate this is the most common cause of coil failure. Never ran into it myself just the first thing that popped into my head.
Plugs are new, with the correct gap. No visible problems with the wires, but I don't have my volt ohm meter handy. Couldn't be the stainless steel connectors I used to replace the rusty spring connectors, either, the problem started first, which is what led me to start replacing them... its just weird. Maybe other coils would blow too, if given the chance, but I back off the throttle as soon as it happens. There's supposed to be a good auto electrical place in Louisville, but lost the address. I'll probably seek them out as soon as I'm done with the suspension...