I think you are missing the point he was trying to convey.
To effectively use the output from an HID source, in an otherwise stock halogen reflector, it will require some serious luck to have a halogen reflector to work with an HID bulb. The emitting pattern of HID bulbs and halogen bulbs are way too different.
I don't think so, at least for an axial-filament halogen.
Check the test #2 at that Daniel Stern link, comparing a 9006 (axial filament) with an HID drop-in. It failed on color (not an issue for off-road), and by being too bright at 5 measurement points, but it was no dimmer than the 9006 at
any measurement point, and a cursory comparison of the contour plots makes the beam pattern look quite similar, just brighter. No luck needed, a similarly-shaped light element in the same place, that's much brighter all over, had
better give a similar beam -- if it doesn't, a botched rebasing job is to blame. (I don't know how prevalent those are, as I have never played the HID retrofit game.)
Even test #1, comparing a cross-filament 9004 to an HID drop-in, showed the HID's intensity being lower at only
one of the prescribed measurement points, and while the contour plots were rather different, the hot spot was still central, and still brighter than the halogen. I'd grant that some luck is needed to get a good beam with HIDs in a reflector designed for a cross-filament bulb, but this particular case shows good enough performance that if I were (bizarrely) forced to choose between a 9004 with the high filament burnt out and the tested HID burner, in the tested reflector, for off-road use
only, I'd go with the HID, and re-aim to the left and possibly down, as needed.
In neither of these cases was the HID kit suited as a low beam, but the 9006 replacement was not scattering light to the sides
instead of forward, as suggested, and even the 9004 kit, with its obviously malformed beam, would still give
better distance illumination than the halogen. It really annoys me when people want to make a (perfectly valid) point so bad, they resort to hyperbole, such as Daniel Stern's claim "the beam patterns produced by this kind of "conversion" virtually always give less distance light", when the data clearly contradict them. At best,
from the very data linked earlier on the page, it could be suggested that some of them throw enough foreground light to override the distance light
improvement with pupil contraction.
In order for a light to be effective, the light must be collected correctly AND projected to where the light is need. Even for off roading, you want the beam to go where you are going, not where you can look at and say "oh my, look at how well I'm lighting up 10 ft in front of me.
Totally agreed, but contrary to some propaganda, an HID retrofit is
not a guaranteed ticket to an over-spilled, under-spotted beam. That's one of the possible outcomes, but there are also much better outcomes possible, depending on several factors, especially the filament orientation and position of the original bulb.
Buying purpose-made HID off-road lights is certainly the sure way to get a good off-road beam, but I think trying an HID kit to save a few bucks can be a reasonable choice, if you do your research first.