Brick...
I am not familiar with the styles of ALL the KBs out there, but I would still pick Yamaha styles over Technics and Roland, hands down. "Why?" you say.

In the case of Technics, I find the styles a bit dated (my opinion) and very cluttered with accomp parts. The loops in the Rolands I have demo'd seem to sound more like loops than the Yamaha's (again, my opinion).

What I really like about the Yamaha products, especially from the 2000 up, is that EVERYTHING can be edited and saved to specific registrations. For instance, you (as a big band and jazz guy) can edit any of the accomp parts very easily so that when you use one of the styles for several different songs it will not sound the same.

3 intros and endings is another big feature I like, as well as 4 standard variations to any style, all of which can be edited to your liking.

As far as the horns and pianos you mentioned, again, I find them to be as good as any arranger I have played. But, in all fairness to your comments, I do not sequence hardly anything. Now that I have found appropriate voices for certain songs, I have no qualms about grabbing them on the fly, knowing they will be appropriate for the sound I want. Of course, there are some I stay away from...but again, that is a personal preference.
No argument here. Just thoughts that came to mind when I read your post.
Eddie