OK, with the ignition ON engine not running, I measured 4.8 amps through the coil (7.7V across the 1.6 ohm ballast resistor).
Sounds about right to me. That's 36 watts -- about as much as a soldering iron, so there you go. Better heatsink that little S.O.B. ballast. Mine's perched on the spring tower, I think I'll move it so it sits flat on the fender to suck up the heat.