Hi Karloo,
I am not that familiar with this kind of music and in jazz music in general.
But I was just thinking that if a style's variation has too many bars and in those bars you want to have many variations of how a part is playing, maybe the style will react "strangely" and not good at all to the various chord changes.
Except maybe if the style is for a specific song and in a specific key where it can be tested to be playable correctly only in a specific way (chord progression) and with the use of more melodic parts.
A kind of melodic parts if I'm not mistaken are the parts of a style that can play a specific melody-riff (like a midi part) and they don't care what chord you are playing.They always play the same notes.
One other way to brake the "monotony" of only 4 variations is to use the intros and endings of the style you don't use, as variations of 32 bars.They are long enough so before they change/end automatically I believe you will be able to press another variation.
So now you can have 8 different variations in the same style (or 9 or even 10 if you don't use an intro or an ending at all)
The "disadvantage" of this method is that you still have 4 fill ins and 1 brake only but you need more of these.
One way I can think of is to copy the style and change it's fill ins
(you don't have to record anything, just "assembly" the drum (or maybe and the bass) fill ins from another style that fit to the original style.
So now you have 2 almost similar styles.
To "connect" the 2 (or more) styles and to be able to change from one to the other you can assign the styles to a registration.
So with the button 1 of the reg you are at the style no 1
and you can play all the variations of the style no 1 using the Main buttons
and with the reg no 2 you move to the style no 2 and play all the variations (with the different fill ins and brake) of that style no 2 using the Main buttons again.
I know that it may sound (or maybe is?) a little or more complicated but if we want to compose an easy tune we can have just 4 chords but if we want that same tune to sound more "advanced" and beautiful we can add more notes,more chords,more complex patterns,more organs etc.
I think that the same "easy" or more "advanced" process can be applied to the arrangements we call "styles".
Sorry for the long post,I hope you didn't just wasted your time by reading it