If you allow people to discuss politics/religion etc., you'll get arguments. That's the nature of the beast. There's no easy way of moderating opinion, because what seems to one person like a valid comment might seem like rabid trolling to another.
The coffee house / DMZ solution is probably the only sensible approach, although it could make a lot of sense to increase the differentiation between that and the rest of the site. I know that's something that a.org has always tried to do, but if it's still a problem then make the differentiation stricter.
I believe that the best approach to moderation is to make it very clear to everyone that you will be extremely strict. Explain that you will terrorise them, rule them with an iron rod, and crush any dissent. Then go easy on them. If people expect strict moderation, they're generally less likely to be shocked when it happens to them, and when they find out that you're letting them get away with just a little bit more than they thought -- why then suddenly you're the good guy rather than the bad guy. ;-) Of course to make this work it would probably be necessary to use a system of permissions that makes posting rights for the DMZ and the rest of the board entirely separate, so that people get the clear sense that there are two separate strands of moderation going on. It should be relatively easy for a troll to get banned from the "main" boards if they start annoying people, but considerably harder to get banned from the DMZ, where annoying at least some people is pretty much bound to happen whether you're trolling or not.
I'd say go with the alternative sites simply because it gives you a way of starting fresh, but there's no reason for a totally clean start - the URLs could point to a.org subsites so that people specifically interested in that subsite can hop straight there via the URL and others can wander in for a look from the main page if they wish.
Part of the problem with all the Amiga sites is that people tend to behave according to what they perceive as being the social norm in the environment they find themselves. Over the years the online Amiga community has become rather twisted and self-loathing, and it's hard to enforce a change to better behaviour. I think it would make a lot of sense to build a new site slowly - don't invest too much into it until you know it's going to work - and keep it in "closed beta" for a while, inviting a small number of trusted people at a time to join in. Hopefully that way, by the time it's ready to go live, you'll have already built up a community with a more friendly and constructive pre-existing social norm that will make it less likely people will drop into the same hyper-dogmatic & trollish modes that are all too common 'round this neighbourhood these days.
