Well I have this theory (after ravaging through a lot of the Forms and their descriptions, and the sources behind them) that a Jedi chooses a Form, but builds his or her own style for the form. Which is why Obi's, Qui's and Yoda's Atarus are all different. They each created their own style for the Forms they picked.
For me a style or form is not just a bunch of new animations, heck, Yellow with a few transition and attack changes could be the new Vaapad as far as I'm concerned, to me it's more the mindset and way of thinking, the strategic value of a certain Form that give you the edge you're looking for.
OJP download links
OJP Sponsors and websites: