...but I also admit I haven't used DNN myself. I have a client which has recently implemented its site in DNN (the technology work was done by a third party) and I couldn't help but draw comparisons with my "favourite" CMS, Joomla! - particularly since there seemed to be several areas that required work by the developer, which I felt should not have done so (sorry, I don't recall the details).
I am under the impression that Joomla! (and its competitors) is more popular than DNN - thus having a large body of third party providers / implementers available - and is seemingly more straightforward to implement. If nothing else, Joomla! et al may be implemented on a wide range of platforms (PHP + MySQL & Apache if you want nice URI rewriting out of the box) and is/are being implemented by people very specifically because of the distributed content management / contribution facilities.
Perhaps DNN is not intended to be a CMS, but simply a framework.
My ha'penny worth.
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