what (if any) legal ramification do North American drivers have to worry about when importing ECE headlamp assemblies for use on North American roads?
It's not legal to import into the United States a regulated item of motor vehicle equipment (which would include a headlamp) that is not compliant with Federal Motor Vehicle Safety Standard No. 108, but that is physically capable of being installed on a vehicle certified by its maker as compliant with all applicable Federal Motor Vehicle Safety Standards (which would include 108), unless such imported item is intended for research and development, show and display, or exportation. However, this provision of the law has long been very low on the enforcement priority list, and when it has (seldom) been enforced, it's been against large-scale importers of blatantly noncompliant lamps. The last big high-profile such bust was nearly 10 years ago; see
here, and was an action taken only after the culprit (APC) ignored repeated warnings. They paid the fine, which was a piddling amount for them, and regarded it as nice, inexpensive advertising and went right on importing (genuinely) unsafe noncompliant lamps. These days, enforcement action against attempted importation of noncompliant vehicle lighting equipment most often focuses on HID kits, which are routinely seized and destroyed by US Customs, though it nevertheless remains easy to buy them in the US.
It is illegal for a party regulated under the Federal Motor Vehicle Safety Standards (i.e., manufacturer, distributor/dealer/agent) to render inoperative or noncompliant any mandatory item of vehicle safety equipment. Installing a headlamp not compliant with FMVSS 108 would count as rendering inoperative or noncompliant the headlamps of the vehicle. Vehicle owners, however, are not regulated at the Federal level. They are regulated at the state level, and state codes vary widely in their permissions and prohibitions on vehicle owners.
"H7 is a newer bulb design, technically quite superior to 9006 for a fair bunch of reasons: it is a much higher-precision bulb in terms of filament placement and focus. Its filament supports are designed so as not to cause stray reflections of the brightly-lit filament; there's a metal-free zone around the H7 filament so the optics get an unobstructed, no-stray-reflections view of the filament. This means the resultant beam pattern can be much better focused for broader and longer-reaching seeing distance and more even road surface illumination. There is no such care in design of the 9006, which produces a substantial amount of uncontrollable light because of reflections off the filament supports; as a result, the optical designer must make unpleasant compromises in beam distribution to keep glare down to the (lax, in the US) legal limits. Moreover, a basic ordinary H7 has much higher filament luminance which gives a much "punchier" beam pattern and that would be the case even if the H7 and 9006 produced the same amount of light, but they don't; a regular H7 produces 1410 lumens; a 9006 produces 1000."
I don't see anything wrong or fishy in that comparison of H7 and HB4 (9006).
So, long story short, they would be an excellent upgrade for my car
I agree; both the domestic and the export Alero headlamps were made by a reputable maker (Magneti-Marelli/Carello, a predecessor company to today's Automotive Lighting company). The domestic lamps aren't bad, but I recall finding the RPO T84 (GM internal code for "export, right-hand traffic") units considerably nicer to drive behind.
I am in Canada, and Mr. Stern says "Both US and ECE headlamps are permitted in Canada (Canada Motor Vehicle Safety Standard 108.1 is the Federal standard that permits ECE headlamps)."
That's correct, and it means there is no legal impediment to your importation or use of the Chevrolet Alero headlamps on your car. However, if I'm recalling correctly the domestic lamp includes the side marker light and side marker reflector functions, and the export lamp does not (those functions are not required in Europe). So in order to maintain the safety compliance of your car, you'd need to add separate side marker lights and reflectors. This is not difficult or expensive to do.
do American residents who are licenced and insured in the US have anything to worry about running ECE headlamps in the event that they are in an accident
That's a good question. If such an incident were to wind up in court or another dispute-resolution venue, a claim that the headlamps caused the crash would have to be supported with evidence much more substantial than "They aren't marked DOT" or "They aren't manufacturer-certified as complying with FMVSS 108". For one thing, the lack of certification does not necessarily mean the lamp does not meet the relevant regulations, so an identical lamp (or pair of lamps) would need to be tested in a laboratory and the results evaluated by an expert. Then there would be the questions of headlamp aim and condition (which are both a big bugaboo in court cases like this no matter what kind of headlamps are in question).
When I am driving my car in the states, do I have to worry about my non-standard (for North America) beam pattern attracting unwanted attention or insurance difficulties in case of an accident?
No. For one thing, a properly-aimed ECE headlamp produces less glare to oncoming traffic than a properly-aimed US headlamp, so there would be no reason why the ECE lamp would attract particular attention to the vehicle. Of course if the headlamp is improperly aimed, improperly equipped (blue bulbs, HID kit, etc.) or misused (e.g., the driver uses the high beams in traffic) or the ECE headlamp is for left-hand traffic, then it
will attract attention and the motorist may get a (deserved) citation.
Beyond that, vehicles are regulated by the jurisdictional power of the state or province where they're registered. States and provinces reciprocally recognize each others' vehicle equipment standards for the purposes of transient motoring, so you cannot be cited in (say) Alberta for driving your Arizona-registered car with window tint that does not meet Alberta standards. If you import that car to Canada and go to register it in Alberta, however, you would be required to make it meet Alberta provincial standards. Transient motorists are, however, subject to the vehicle usage regulations of wherever they are driving through. If a particular state or province says you cannot use your vehicle's fog lamps while driving more than 30 mph / 50 kph (or whatever) then you are responsible for knowing and obeying that requirement even if it differs from the fog lamp usage requirements of your home state or province where the vehicle is registered. Canadian (and Mexican) motorists are permitted to drive their vehicles into and within the United States whether or not those vehicles comply with US Federal safety standards. It's always interesting to go to Arizona and see the many Mexican-plated vehicles with ECE lighting equipment. Occasionally one sees a Canadian-plated vehicle with ECE headlamps (1st-generation Smarts, '86-'94 Saabs...), too.