Michael,
Thanks for your post, really interesting.
I thought my question was a little ignorant, but I seemed to have hit a spot... !!
From the posts it seems DNN with a mix of modules etc can offer a real alternative. However I still have a nagging feeling about those "clients" who have already bought their licences and want to get the most of their SP installs.
Also I keep forgetting that WSS is free so this question only becomes valid when one is forced to consider MOSS2007 where one of the big issues is office integration.
Thanks again everyone....
Sam