I have not SEEN many 6X9 designs, but have heard several folks talk about doing it. Mainly for OB if memory serves.
If you do a search here for "6X9", you might get several good hits (I just don't have the time right now to dig through and find them right now). The one that comes to mind is (long lost) member "JohninCR" talking about making some radical folded 'W' baffle with a bunch of automotive 6X9 drivers.
Hope that helps you Nightshade,
Bob