Frans, there is a way to achieve different patterns for different chord variations within the Yamaha Style File Format. In fact, some Yamaha factory styles make use of this feature. However, if you want to make a style like this yourself, you have to use a 3rd party utility called CASM edit, because the on-board Style Creator does not give you access to all of the required parameters.

There are also undocumented parameters that control the behavior of Roland styles, such as the "Retrigger" behavior (which I consider quite important.) However so far there is only some speculation, and not a 3rd party utility to make user styles with full control of this parameter.

I have really come to appreciate the way Roland implements certain features, and their highly logical Chord Intelligence which gives a wider variety of common chords with simplified fingering. But on balance (and taking into account available third party utilities), I think Yamaha has better possibilities for creating user styles. My $.02. -Ted