These are worthwhile ideas. The reputation system based on upvote history is obviously worthless. User Authority is slightly better but the idea is sort of half-baked and and the connection between engagement and rewards is so unclear as to not drive much in the way of increased engagement.

A trust/endorsement system is a very interesting idea because it relies on human interactions and judgement. A trust-based system like that could serve as the basis of an account based curation system for one thing.