I've switched halogen headlights from DOT headlights to E-code headlights on other cars.
I considered not ordering the BMW with Xenons and switching to E-codes afterward, but it would have cost me about the same as just ordering the Xenons. Plus it was easier. The DOT Xenon beam pattern isn't too different from the E-code pattern.
2008 E91 station wagon 18K miles "Classic" BMW inline six, six-speed manual transmission, Alpine, Terra, Xenons, ZSP, ZCW, ZPP, PDC, CA, alarm, M shifter and M brake handle, Euro rear fog light switch, Euro aspheric mirrors, rear power outlets, Dunlop Winter Sports, Garmin nüvi custom cupholder mount, Lidatek, V-1 built-in remote display, tire pump, jack, floor mats, sand, dog hair, several pairs of smelly old running shoes.