[brucepick]

Lots of discussion recently in this thread regarding beam pattern, aim and their effect on brightness. I'll add some points from my experience.

1)
The o-ring gaskets supplied with my LED "bulbs" were too thick. Reviews of those bulbs by other users alerted me to that possibility. Local hardware store to the rescue.

With too-thick o-rings, the bulbs did not go fully into the headlight housings. Result: poor brightness and ho-hum alignment. Which actually was off.

2)
Once properly installed I needed to adjust the aim. Please see my photo on first page of this thread for the result.

Actual beam pattern is a rectangle, not the horizontal line type thing from a typical halogen. I adjusted so that the TOP of rectangle now stays at the same level as I back the car away from the wall. That is key. This way, at any distance, the "cutoff" stays at headlight height and does not move upwards as distance increases.

3)
I agree with sendler (Scott) in that while the LED emitters are not identical in shape to the filaments of halogens, they have gotten small enough so their effect approximates that of halogens. They will only improve as they get smaller in time.

4)
My car uses separate bulbs and housings for high and low beams. This makes it easier to optimize the bulb design for its job. I expect cars with a single dual-purpose bulb on each side may get worse results from LED conversions than I did. But if that's true, results will improve in time, as emitters get smaller.