Interesting also, Ron about Dave and Daryl's decision to move Wilson Subs from 18 - 15 - 12. It has made me think on the dual-opposing 24" Funk...perhaps considering instead stacked dual-opposing 12"? Wilson subs are also focused on sub35 or sub30hz territory...so a lot of air displacement, but his view is cone speed also helps create a more realistic sense of space.
So 4 per cabinet...and 2 cabinets (1 for each channel). Same surface area, probably less air movement given the excursion of a 12 vs a 24...of course, by contrast, I know Nathan Funk is a fan of larger cones because they move the same air as a smaller cone but 'can' exhibit lower distortion because the larger cone is not working as hard whereas the smaller cone has more displacement/movement/excursion to move comparable amounts of air.
Still...something perhaps I will revisit with Nathan when next we speak. Thought provoking interview!