in fact we do that already. The site is configured so that we can add (and remove) forums fairly quickly when we need to, so that's not a problem.
At the moment we're watching this forum to see how it goes; you'll appreciate that the main consideration from our point of view is the effective use of resources - of which I'm a part. It takes time to watch the forums, and adding new ones means more work.
I think we'll be fine with WebDesign; we have one or two ideas up our sleeves, so keep visiting to see how we develop things over the coming weeks.