I have a Jeep Wrangler TJ that has had a stock headlight failure, so if I'm going to replace one I might as well go the whole hog and replace both.
Good idea, a TJ Jeep is old enough that it is probably ready for new lamps.
1. Don't Do HID.....it's dying and has too many potential issues.
That is a non-sequitur, because you are not an automaker making plans for a new model. HID headlamps and repair parts (bulbs...) will be around for the foreseeable future. It is only "dying" in the sense that it is largely no longer considered at the new-vehicle/new-headlamp design phase.
2. Bi Xenon is the 'best' around but crazy expensive.
Two things: (1) BiXenon is HID. (2) HID headlamps, even type-approved ones, are not allowed in the UK without lens-washing and automatic leveling systems. Both of which can be added, but it's expensive to do so in addition to the expense for the headlamps themselves.
3. LED would therefore appear to be the best 'bang for buck' currently.
Yes.
Having watched the excellent (IMHO) headlight revolution youtube vids
I couldn't call them "excellent" in terms of presenting sound, reliable information. They're entertaining if you like looking at pretty pictures of headlights and light beams, but photos -- moving or still -- are not a useful or helpful way of evaluating headlamps.
Yes, this is a good LED headlamp that is available in a type-approved LHTraffic version with a built-in front position light (UK English calls these "side lights" and it's a function you need on your Jeep)
Not available in a type-approved or LHT version.
Available in LHT type-approved with front position lamp (and daytime running light, for that matter) and this is the top of the heap in terms of performance.
Cheap junk, not available in LHT or type-approved.
These are coming in at about £200 each which seems pretty high if I'm honest.
Am I missing something?
Yes: Complex current cutting-edge technology (LED headlamps) costs more than obsolete, primitive 1971 technology (H4 headlamps). You get much better safety performance -- ability to see at night and in bad weather -- with good LED headlamps, but you have to pay for it.
Cheap junk not worth using. If you are sticking to halogen headlamps, get a set of Cibie (Valeo) part number 082439 units and use Philips Xtreme Vision (or new Racing Vision) bulbs.
RHD is a colloquialism to indicate the side the driver sits on and therefore which way the beam should go, it's synonymous with LHT
No, it really is not. The placement of the driver within the car (LHD or RHD) does not matter to the headlamps. The placement of the car on the road (LHT or RHT) does. Remember, LHD cars are allowed in the UK, but they have to be re-equipped with LHT headlamps instead of the RHT headlamps they would come with in their "home" (RHT) countries.
(If you said LHT in the UK no-one would understand what you meant)
Well, you have to use the local idiom, "left-dipping headlamp" to refer to what you're trying to talk about. If you're talking about the traffic on the roads, you say "Left-hand traffic" and everyone who's in a position to care will know what you're talking about.