I'm 100% manual curation. The laziest I get is to sometimes drop my last 2-3 votes per day on large comments made on posts from users I follow. For me, those hidden incentives you mentioned are big. I want to reward real people making quality content but also people reading and taking the time to respond (meaningfully). That's how I see HIVE growing/succeeding. If everyone is just extracting rent, this place will die.
I think it's a great idea to try and reward manual curation for exactly this reason, and I hope your revenue idea pans out.
My low tech idea is based on my situation. You've delegated me some HP, which makes my manual curation worth more. Not enough to be meaningful on post rewards, but nicely sized for comments. Perhaps you could white list people in OCD or just the community in general and delegate it out. You could probably use HIVE stats to track their votes over time. No self-voting, spreading votes between different people, etc.
The reward of course is baked in: more HP means we'd get more hive ourselves. Call us something fun like "The Comment Curation Brigade" CCB 😄