That is a very useful and succinct review by Lewis; I hadn't read that article.
I have never run into anyone claiming that there were not systematic
cross-national differences in policy networks, myself. Too obvious to miss--e.g.
the unique role of American Congressional committees etc.
I worry that those on this list who tend more toward barefoot empiricism or are
just interested in analyzing some particular bunch of policy changes get scared
off by all this heavy theorizing/typologizing. What we know about policy
networks offers a very good checklist or set of questions to ask about your
policy--you will see things you might have missed otherwise.