I think we agree 95% (+/-).
On the basis of the reports on the HD thus far, mentioning only very slight or no visible improvements at all on CA reduction, I tried to find (guess really) a possible explanation in the one important thing Leica didn't change, the coating. In my opinion this coating is very important for the specific character of the Leica, in the way that it sets it apart from other makes, and appeals to different people. So I think Leica would be very reluctant to give up this identity (imagine them suddenly adopting the Swarovski or Zeiss 'touch', wouldn't we be greatly disappointed?).
Now, to my eyes this 'Leica view' can be characterized as a kind of prettified (magnified, sharpened up) image, in the way that colour saturation and contrast is just a bit 'better than life'. There is an explanation of the phenomenon, written in defence of the Zeiss (FL) approach, by Stephen Ingraham: http://www.zbirding.info/Truth/contrast/contrast.htm
Now, I won't go into any arguing which approach is best (I just happen to like both). My point is that I think the reason for the quite strong CA found in the Ultravids could very well have something to do with this 'not completely natural contrast'-character.
Back to the proper issue under discussion: maybe the lack of visible improvement in the HD over the non-HD Ultravid could be explained by the phenomenon as well. In the way that the coating simply doesn't allow the subtle possibilities of the better glass to flower.
Just a thought.