Denied Stop leech spam

This isn't the first forum I'm running and I'm actually able to share a bit of experience with a system like this.

We basically had this system where new users were in a let's say "leecher" group which was their default group when they signed up for an account on the site. This group had the ability to post, but the posts did not show up for anyone except staff members, waiting for approval. After about 10 posts (iirc) which got approved by staff, the user would be automatically promoted to a regular member group with no posting limits and the ability to post without staff approval, basically a normal member.

It reduced low quality and spam posts by let's say 95% (cause you always have some normal members which don't behave in their best way too) but there were some problems with it:

• It reduced the general forum activity a lot and I really mean a lot.
  
• We were only a team of like 4 staff members, 3 from the EU and 1 from the US. If someone with a different timezone than the EU signs up and waits for his posts to be approved he has to wait several hours since most staff is asleep, at school or at work, which made them instantly quit and never came back, which I actually understand. I wouldn't bother with that myself.
  
• Staff had a lot of work to do. Going trough hundreds of posts every day wasn't something we enjoyed after like two weeks. Doing reports every day is fine, checking out some posts is fine but this was just too much.
  

There may have been several other problems but I can't even remember them anymore since we dumped the system after like a month or two again.
Blaze was staff at this time too so he might be able to give you his own input on it.