That was a fun chapter and I'd love to see Severus Snape's face after his team gets drubbed like that. It should be rather interesting to see where Harry's romantic interests aim as the story moves along. I think that, with Peter on the loose, it's almost a certainty that Harry will end up representing St. Trinian's in what will become a quad-wizard tournament. I rather suspect that St. Trinian's girls will also know how to properly deal with Rita Skeeter; she won't know what hit her.
I enjoyed that discussion of Order vs. Chaos as opposed to Good vs. Evil. To BJH, I'd say that the D&D matrix reminds me very much of the Pournelle Axes (q.v.) for governing phiolosophies.