Sounds like a good way to go with the software design IMO. Personally I interested in PunBB.net because I need a software I can fully integrate with my current site. I haven't look too much into the code yet (will be a few day until I have time) so I don't know how that goes yet. Of the other things you mention, ssp. the lack of a business layer is concern for me.
Btw. I hope to see some more development on this project. I can see SVN is "active" again, but I haven't found any where that says anything about the future plan.