MetaFilter does that, and doesn't seem to have problems with quality of discourse. Of course, HN as it stands doesn't seem to have significant problems with quality of discourse, either, so I'm not sure that HN needs either solution; discussion here is already far superior to what you find on the vast majority of sites.
> MetaFilter does that, and doesn't seem to have problems with quality of discourse.
What also helps the level of discourse at Metafilter is moderation to the tune of showing up in threads, deleting comments, and saying "knock it off" when things get particularly bad.
Sure, but that's done on a case-by-case basis, when things actually do get out of hand; it's not a universal, preemptive moderation system that's built right into the structure of the site.
There's no reason the fee can't vary depending on the location of the person signing up.
I also think this is a far better solution than "pending comments". I'm not convinced that either solution is ideal, but I fear "pending comments" has the potential to silently strangle HN.