1. For each topic, get a list of the distinct users who posted there in the last 24 hours.
2. Give the topic a score equal to the sum of each such user's total earned merit.
3. Sort by topic score descending, and secondarily by the usual last post time.
Sounds interesting but perhaps this can be implemented initially as an option to try it out?
It seems to me that this could prevent some (most) threads from ever showing up the front page. Some others would be likely permanently parked there.
Also if I want to comment on some scam I would likely bump it to the front page (which happens now too but the front page bump in the new system would be far more valuable). An opt-out from the score would be nice.