How low the cabs go is something I've asked Mike about. 18 Sound 112 --> Flex --> 46 --> MAS 109, I believe, in order of increasing low frequency extension (meaning the MAS 109 goes the lowest before hitting its -3 dB point). Not sure where the newest 112 falls in there -- should go lower than my 112, I think, but don't know where it fits relative to the other cabs.
That only tells a small part of the story, though. Though the Flex goes a few Hz lower than my 112 with the 18 sound woofer, its "bump" (I think it might be more than just a frequency response thing, but that figures in, too) is higher up than the 112's, which is pretty brutal down to the bottom of its register -- that punch in the chest vs. kick in the gut thing (the Flex can kick and the 112 can punch, but I'm talking about their native strengths). If you listen carefully under the right circumstances you might hear that the Flex goes lower than the 18 Sound 112, but that's not necessarily the first impression they'd make, and relative extension wouldn't be the first thing you'd notice listening to the two next to each other.
