It just seems pointless to explain because you're trying to justify an enclosure that would fit two of your subs and still sound great vice just one. I'd understand 7 cubes if you were tuning to, say, 25Hz, but not for a daily system.
But it has already been said. The enclosure determines the sub's output and articulation. Those who complain about boomy subs aren't designing the right enclosures for them. You do have a tradeoff of lower extension at the expense of a slightly less upper-end extension. The size, however, has nothing to do with SQ.