Everything that I have read from expert sources says that leveling, auto or manual, is for load-based adjustments only (as in, put a heavy load in the rear of the vehicle and that tends to angle the front-end upwards a few degrees so compensate for that by aiming the lights back down a few degress) and not for real-time hill/dip adjustments. Apparently, all auto-levelers are too slow to compensate for changes due to road geometry, except perhaps the mechanisms on some 2004 saabs which claim millisecond reaction times. In Europe, if they don't have an auto-leveling system almost all cars have the manual adjuster even if they have halogens, there is just something about DOT specs that makes that rare over here -- only nissan/infiniti seems to be bucking that trend with their newer models like the murano/fx and qx lines. It is apparently a popular mod for a lot of Euro-brands like VWs to add the manual adjustment because usually most of the mechanism is there in the car, just the dashboard switch has been removed.

Glare is largely a function of the light housing and lens and there too DOT versus ECE spec makes a big difference. DOT actually requires a fair amount of glare because they want some light spray above the cut-off in order to provide illumination for signs as well as to increase visibility over hills and that sort of thing. ECE spec projector housings have a very sharp cutoff, often with an upware flaring on the right to illuminate road signs. I have noticed that the stock VX beam pattern is very similar with a remarkably sharp cutoff for a halogen reflector system (versus a projector, either halogen or HID) and a flare on the right.

The DOT has recently made it illegal in the USA to sell HID retrofit kits that are not projector-based (as in just pop these Xenon bulbs plus ballasts in your standard halogen reflector system), or rather they have just started enforcing a technicality in the law that made them illegal since day one (and along those lines, labeling a product as "for off-road/show use only" does not make a bit of difference as far as the DOT cares). The unofficial word on why the DOT has started this enforcement is that it is because of the large number of complaints about glare which they have decided/determined are due mainly to HIDs installed in housings designed for halogens rather than properly designed systems which should, in theory, have less glare than even any DOT approved halogen system.

So, to go HID you pretty much have to go with a projector based retrofit and for the most part you have to use OEM parts like those from BMWs or Audis. In my research on the subject I haven't heard anyone else mention any particular benefit, like ease of installation, for maxima OEM HIDs. From what I can tell, Audi, particularly A3 (a model not available in the USA) HIDs are prized for ease of installation because their size is fairly small, I think about two inches in diameter. The Honda S2000 HIDs are also well liked for their sharp cutoff (even DOT models) and extra amounts of blue in the beam (which is due to the shape of the projector housing and lens, not the color temp of the bulb as all OEM HID projectors have color temps in the 4100K to 4300K range, until the bulb has aged significantly resulting in "color-shift" which increases the bulb's effect color temperature).

For those who are interested in all this stuff, including info on doing a manual retrofit using OEM parts from other manufacturers, the best source of info that I've found is www.hidforum.com although there is definitely a lower SNR there than a place like the vehicross.info.