As well as light scatter, aftermarket HID's in reflector headlights will always look, well, aftermarket.
There is a Mk5 Golf that I see around here with them. I was next to it in my Passat (with a HID conversion) the other day. The Golf's headlights looked like big blobs of bluish tinted glare, where as my projector lights had a sharp, focused almost piercing stare. Just like OEM xenons.
As said before, HID main beams will react too slowly, and what about your DRL's? As for foglights, they will be more likely to light up the fog rather than the road below it.
I don't usually agree with you, but in this case your top tip is spot on.