I do feel this forum gives people a greater feeling of participation and control than a mailing list would.
For example one mailing list I'm currently a member of sends out 20-30 emails per night containing insights from seemingly unrelated topics, perusing through the trash till you can find any relevant information can be quite disheartening.
The thing with forums, you have to become accustom to using them. The option is there to show all previous topics from the forums creation but its default view shows only recent ones, as a result you will get repeat discussions from people new to forums.
Paint Finishes???? Doesn't that have its own chapter in the build manual (Chapter 25, I think) and there are chapter specific conversation areas on the forum but most folk dont get familiarised with the forum so just dump everything in 'Coffee House'