It's good to know that community leader see the problem, trying to find the solution and asking for opinion (that's how I read your proposal). I bet we will have to get back to the discussion after the hardfork. There are many ideas in comments how to improve the system, here is mine:

• anonymous downvotes
• increase the downvote mana to 100% of upvote mana (both with same rebuilding rate)
• after every downvote burn tokens instead of sending them back to reward pool