I tried the 2x sets of HID method, one for lo one for hi etc. When switching to hi, you'd get the usual pulse then it would take a while to 'warm' up. Looked somewhat silly.
It worked ok like that for a few days, after a week one of the ballasts burnt out.... due to the owner flashing the main beam, let people out of junctions etc.
The ballasts aren't deisgned to be switched on and off rapidly, that is why proper setups adjust the light beam to switch. The ballast is constantly powered.