codimasta
I happen to totally agree to wire the glow plugs in series. I am not sure if the Mac Daniels can drive this or not. The problem with the parallel system is that WITHOUT fail, one set of wires and one plug have more resistance than the other. Now only one plug really gets hot or comes on at all.
I also have used the micro switch on board glow system. One problem that did happen on one installation that you should be aware of. I did on one Plane have radio glitches as the switch opened and closed. Consider to put a capacitor to kill the arc across the output wires.
The electronic ones do have the added good point that they self cut off when the main receiver switch is cut off. Yeah ok I have forgotten a few times......now where is that transmitter.......home!
Good Luck,
Twinman