My system has not had a new enough set of libraries etc to run a current docbook setup ..until maybe now (I think). I've just installed Debian 3.0r1 stable and haven't checked the "new" docbook yet.
I think docbook is an adequate working format in that it can output to the various web (and other) publishing standards.
Still, I think the docbook publishing format needs tweeking for reader's sake, because one can publish a series of documents more reader friendly than standard output from docbook. I'm working on a proposal for changes. Since docbook is an evolving standard, the doc publishing format will hopefully improve as docbook improves (and at little additional effort). Alternately, we can create a variation on the docbook format at any time without affecting the content (much).
I haven't had a chance to learn/use ETP yet, but like Jade's idea. Perhaps there is a way to get the best of both worlds: Is there some way to integrate the docbook files to be editable/updateable through ETP?