OK, some results are in.
In a word, ridiculous. In several, I don't know yet.
High-brightness temperature H4 halogen bulbs in Hella E-code 6024 housings in a Classic:
Low beams:
High beams:
LED bulbs in the same housings: remember that these are "rated" at 3000K low beams, 6500K high beams:
Low beams (next to a Toyota Echo with LED bulbs in factory housings designed for halogens):
High beams (next to the same Toyota):
The light distribution on both high and low beams is far better on the Classic than on the Toyota - but I am not sure about LED vs. halogens.
Yellow headlighs look ridiculous, and they don't feel right. Maybe I get used to them (if I don't get pulled over), more likely - not. I need to ask people I drove behind how good or bad these lights blind the drivers ahead. Visibility for me - definitely worse than with the halogens, but it is very hard to say in any quantitative manner.
Fit - no issues; however, there's no way to waterproof the housings short of RTV'ing the hell out of the mounting surface and around. Definitely far worse than H3 bulbs with the rubber boot around them.
Stay tuned...