Good warning for all to beware.
I also have known guys that have a bite in the tank for years on end. This particular one had a thriving SPS tank and every time I put my hand in there, I jumped from the bite and I even knew it was coming!
My point is that the current is probably not to blame. I would blame the copper coil inside it. After all some things lived right? If current was this detrimental it would be a much larger issue in the hobby, Magdrives notoriously leak electricity.
The fact that you said your pods went first also is a clue that it was copper, pods die, fish live.(I would bet that the fish that died were more delicate or the largest, which need more oxygen and with the dying reef, water quality plummeted quickly) Did you ever do a copper test? If you run carbon in your system then it could have been buying you time, I just can't see electricity having such an overnight effect on the corals.
In my experience if it is enough voltage to kill immediately, then it is enough to knock YOU on your butt when you touch it, much more than a bite.