I'm staying out of the math, except to wonder what is a bass doing out to 15 or 16khz . . .
My impressions of ELF/BagEnd:
--I totally agree that the concentric high drivers are MUCH smoother than the typical horn in most bins, which I routinely dislike. I did like the 410 Hartke bin with the 5 in the middle, as it was smoother than a horn (and I'm no Hartke fan, but I do like that bin).
--The ELF bottom pass is very smooth: You don't really hear it at first, since we're usually used to ports, folded horns, transmission lines, all designs with a lump in their sonic signature. It really plays with your head that this is a sealed cabinet, just big enough to hold the speaker.
The double cabinet 18 with the 210/highdriver cab on top would be my dream rig. Just as going from a head/cab to a component rig is a big jump in fidelity, from a regular component rig to the ELF/Bag End rig is that big a jump again. But remember, it's like the tone in a good recording studio. With the right power, it just gets louder and will not break up . . . which is a revelation for a lot of us. There are lots of people who will not like it, it just won't be grainy and lumpy enough. If you need lots of skank and sturm and drang, keep the SVT or your SWR rig.
It's like going from Jack Daniels to Crown Royal.
Jack will sure get the job done, but Crown is just sooooo smoooooooooth . . .
J o e y