It is a good idea. I would love to see this evolve by letting the marketplace sort it out. I think Reddit would be the perfect platform. The admins should create an efficient native micropayment system (or they could just bless changetip).

Integrating it with gold should be straightforward.

And then let each subreddits’ mods choose a way to use it (if at all).

Very quickly the best methods would become obvious and gain wider adoption. In a way, all of reddit would ‘upvote’ the best protocol for comment micropayments.