All of the existing 'forums/lists' have one problem or another, and a solution to fix 'all' those problems is not currently available ;)
The KEY element which is missing from many of these 'new fangled' on-line forums is a proper functional email interface. A number of the lists I frequent on yahoo have been 'improving' things by introducing web based forums, but having to keep going and looking on-line even if you have had an email saying someone has posted something is just impractical when involved with more than a small number of lists :(
Even cnczones email digest does not replace the immediate and local monitoring of lists, and the time it takes to download all the crap along with the long list of messages that would normally be stored locally. I've no objection most of the time to on-line forums, but if someone asks a question and I answer it, I like to be able to do that from my email client and archive the thread locally as I work on it. Progress is currently not improving anything and having to download
100's of k of data just to read one new post is not progress ;)
I don't think it would be such a bad idea. As many others here, I tend to frequent the US based forums and it is always interesting to see some of the superb projects, tools, and other items that people have conceived and made.
Although I don't have interest in models per se, perhaps a UK version of the HSM site directed more towards the workshop and machining projects would possibly be quite interesting.
It would be a great idea if the user interface was slick. I don't think I've seen a web based forum which is as slick as a text based newsreader yet. I find most of the web interfaces really clunky. Solve that and I'll sign up!