[sperry]

Alright... how's this look.

Everything is totally redundant and operates entirely at the headlight, with only 1 more relay than your original drawing. The only wire you'll need to run is a power line from the battery to each light, everything else can live right at the light itself (though I would recommend some high quality weather resistant relays).

As far as the way it works:

When the LOW is switched to ground, the ballasts get fused power from the battery. When the HI is switched to ground, the shield solenoids are activated, as well as the right hand relays, which in turn grounds the relays that are powering the ballasts.

If I remember correctly, when switching from low to hi, there is an intermittent state where both low and hi are grounded, so you shouldn't have any weird issues with cutting power to the ballasts. Nor should you have problems with hitting the high beam passing lights with the lows off (though I'm not sure that flash to pass with HIDs works at all since the ballast takes time to warm up...)