Surely the as the whole lamp moves up and down together then they would be ok? It's more likely that there's a legal or technical reason why you can't have an HID bulb for main beam. I know they take a while to come on is that why?
Humpy
As I understand it, retro-fitting HID's is not EXACTLY illegal. Grey area and recommendations from the Dot yes, but here's why I say this:
1) - My Carlton has had HID's fitted (no washers, no level sensors) for 5 years. 5 MOT passes because they pattern is legal and not too bright according to my MOT tester dude.
2) -The HID burners are covered, so they CANNOT flash oncoming drivers, or (as some people have said on other forums) give anyone arc-eye........which is impossible as there is no naked arc, it is behind glass!
3) - I don't recall there being a LAW passed or amended or even MOT rules amended or modified, that states retro-fitted HID lights are in fact to be deemed illegal WITHOUT washers and levelling system fitted also.
OK, I might have not seen anything, but that doesn't mean there isn't anything to say I have to remove the HID's from my Carlton, so until Plod tells me and produces evidence, or the MOT tester fails it, they stay.
I have HID's as 'Hi-Lo beam' ( usually just low beam in a Carlton) plus the "driving" or "spot" light is HID. The Hi-Lo side if things is fine - the spot lights are pretty awful, as the beam pattern is all over the place.
Back to subject - Osram Night Breaker bulbs..............
I may have been a little harsh when I first said they were rubbish, but I still feel they're not as good as whatever are fitted to the now defunct Elite of ours, so I shall swap out the headlight units...........