I was reading through it again last night, and thinking about how to apply it to my College Ritual Book Magic rules. At first pass, the two don't mesh very well: Magical Styles is very focused on having stylists advance by learning specific spells in a fairly specific order, while CRB Magic mostly replaces learning individual spells with learning spell colleges as Very Hard spells. There's not really a lot of overlap between the concepts.
As I thought about it more, I realized I was very wrong. An ordered list of spells is conceptually a set of grimoires. For instance, the first two Circles of spells in the sample Onyx Path style could easily be two grimoires: the Neophyte's Primer and the Black Tome of the Gravekeeper. Furthermore, to encourage the use of styles, the bonus for the Magical School Familiarity Perk should be changed. Instead of allowing a stylist to learn the school's public spells at any time, the stylist increases the grimoire bonus for any of the style's grimoires as long as he has the grimoires for the previous levels.
Example: Bonegnawer is a Reanimator (Fourth Circle) of the Onyx Path who owns the Neophyte's Primer, the Black Tome of the Gravekeeper, and the Book Ebon (a 3rd Circle Grimoire with 7 spells in it). He finds an Onyx Path Grimoire containing Gift of Letters +3. Even though Gift of Letters normally has a prerequisite count of 5, Bonegnawer is only at -1 skill to cast it because the grimoire counts as a +4 grimoire for him. If Maldo the Magnificent steals the grimoire from Bonegnawer, Maldo casts Gift of Letters at -2 because he is not an Onyx Path stylist. Similarly, when Bonegnawer's apprentice Darklight sneaks into his master's study and tries to study the grimoire, he also treats it as a +3 grimoire, because though Darklight is an Onyx Path stylist, he only has the Neophyte's Primer and doesn't meet the prerequisites for using the grimoire.Magical styles are a very neat concept, and I think tying them into CRB Magic actually works better than the standard GURPS Magic rules.
Edit: Added a title. The things you forget if you don't update your blog for a month...