The way I use dpkg-scanpackages is to have a single, central repo machine, with independent repositories for different projects. Publishing a .deb is the same for any project - scp, then ssh and run make in that project's directory. I have a very short shell script called publish-deb which does exactly that.

It could be that I've just not bumped into problems which require them, but I've not found a project which offered features above the set this gives you where the trade-off is worth the complexity. "Everything works this very simple way, there's almost nothing to learn" is very persuasive.