I am sorry, but with all due respect I do not agree with you on some points.
Iron and its alloys (commonly used) are less conductive than aluminum, but they are always metals and so excellent conductors.
The geometry of disc with magnets is symmetrical, one magnet want turn disc in one direction and symmetrical magnet do the same in opposte direction, so stupidly one cancels the effect of the other. Thus the disc is free to rotate due to the eddy current braking effect with aluminum or iron rim indifferently. In my opinion.
The dynamo pinion is pulled on side of tire, pinion deforms the tire, so the rotation of the wheel is braking strongly, the side of tire is worn by the contact with the pinion due to friction.
I don't know if you've never noticed that the side of the tire heats up when using the dynamo.
This is a lot of wasted energy, as well as damage the tire. When you said: "it'll have almost zero friction slip loss
" doesn't find me agree.
Sorry for divergence.
PS: Apples and oranges are both fruit, belonging to a common category are comparable. The rest I agree with you