I’d like to give it the HN equivalent of Reddit Gold... maybe HN could implement something along those lines but instead of keeping the money and removing ads, the money could get donated to something like the EFF?

My favorite thing about HN is that the votes don't matter that much and comments stand on their own. I would not look forward to that addition, unless only the receiver was aware of it.

A cryptocurrency address in poster's profile would do the trick

You can click "favorite" on the story itself and save that to a separate space. Can't favorite individual comments though (yet).

Edit: Yes you can. Click your profile and click favorite comments at the bottom.

  To add a comment here, click on its timestamp to go to its page, then click 'favorite' at the top.

I think the words "Excellent comment" alone show the parent comment as truly an excellent one. I agree, upvotes for both!