I just received one of each of the cabs (ported/straight 1x12, sealed/slanted 1x12, ported/straight 2x10, and sealed/slanted 2x10) and spent the last couple of hours jamming through them all. First impressions are that these are even more compact than I remember. Super easy to schlep, and the two 2x10's stacked is notably smaller than your average 4x10. Interestingly, they each have a fairly distinct voice; no two sound close enough that you'd confuse one for the other, once, you get used to them. They ship with covers, which is very nice, and a thin 1/4" to 1/4" speaker cable. Each cab has one 1/4" jack.
Comparing the stack of 1x12's to the stack of 2x10's, the 1x12's are a bit more warm/round/vintage, and the 2x10's are a bit more cutting/precise/modern. I wasn't sure how well they would mix together, but I ended up really liking the sealed/slanted 2x10 on top of the ported/straight 1x12. This seemed to be the "best of both worlds," in terms of a full/round tone that was still very clear and precise. My favorite standalone cab, so far, is the ported/straight 1x12.
The Eminence components are very nice. The 12's use the Kappalite 3012LF, and the 10's use the Deltalite II 2510-4. Each of these drivers gets up over 2k, and the BGH25-8 tweeter goes down below 2k. I didn't hear any real obvious holes or valleys in the frequency responses, but there are a few peaks, I am sure. Especially when used as a stack, these cabs are fairly well balanced and full-range, but again, they each have their own voice.
Much more gig and bench-testing to come, but I wanted to share my initial thoughts. So far, Quilter has impressed us, and the BB800 is performing very well both on the bench and at the gig.