[...]It is a cold and rainy day today, plus I am tired, so I did not ride the bike tonight with the HID installed yet. So some of my concerns, below, are based only on theory and non-riding observation.... [...]
OK, now I have a nighttime ride, and had to go a good ways to get to an area with no street lights and no cars so I could make some real observations.
Yes, they are brighter, no doubt now. And the 4300 color is excellent, seems the same as on my Infiniti. I immediately noticed the top cutoff is lower than on the halogens and had to stop several times and aim them up higher.
They are a lot more distracting than the halogens because they are "bouncier". I think there are two causes for this: One, there is a lot more mass than just bulbs in the housing now, but more importantly, there is a BOTTOM cutoff that is much more pronounced than with the halogens. So the areas near the bike have much less light that further down the road. All the vibration and bouncing of the bike is clearly relayed back to the rider from the bottom cutoff and it is going to take some getting used to. Also, there are a few horizontal darker stripes in the beam. The overall pattern is not great, worse than the halogens, MUCH worse than the Infiniti projectors. I agree that there is more scatter with the A&R HID than the stock halogens, too. The scatter is not awful, though.
I was worried the high beams would not be as effective, since [unlike the halogens on high beams] they are only using half the reflector. I think those fears are unnecessary.
It is going to take me more time to aim them properly. I am always afraid of blinding people, so I will have to go do some additional tests and adjustments later. I did the best I could while actually riding to try and make sure the low beams would not hit mirrors of other cars. After those adjustments (mostly raising them), when I got off the bike (side stand) and walked 100 feet away, the low beams seemed to be below my knees, which seemed surprisingly low.
Overall, it is an improvement over halogen. Once I get a few more trips at night and finish adjusting, I will know how much of an improvement. I am spoiled by expensive-car HID projectors and might have had my initial expectations a bit too high. I have no experience with "HID kits", so I don't know what is typical.