On 4., in addition to the incentive problem, there’s also the problem of matching the right reviewer to reviewee such that the counterfactual value generated is high enough, which will depend greatly on the post and the reviewer. I think this is harder than the incentives problem. Downsides of not solving the matching problem could be people spending time reviewing posts that might have been better spent, or posts that are promising and need reviewing get reviewed by whoever is most incentivized/has time on their hands and then people think it’s been reviewed already so the price for a 2nd review goes up.
On 4., in addition to the incentive problem, there’s also the problem of matching the right reviewer to reviewee such that the counterfactual value generated is high enough, which will depend greatly on the post and the reviewer. I think this is harder than the incentives problem. Downsides of not solving the matching problem could be people spending time reviewing posts that might have been better spent, or posts that are promising and need reviewing get reviewed by whoever is most incentivized/has time on their hands and then people think it’s been reviewed already so the price for a 2nd review goes up.