Adire AV8 Woofers

My upcoming MTMs will need some kind of additional support to get the bass extension that I want. Originally, I was going to simply build a sealed Tempest Sub, but a few things made me reconsider.

Currently, I am entertaining the idea of building stereo dual woofers; that is, two separate sealed boxes, each housing two forward firing woofer drivers. This is advantageous to the mono sub because I will probably replace the MTMs in a few years, and the 2-ways I have planned to replace them would need additional midrange. I'll probably build a mono sub later, anyway...waiting to see what Adire has cooking for their next-gen sub drivers.

I've looked at the numbers, and it looks like the Adire AV8s hit the correct frequencies with a decent amount of bass extension. Has anyone had any experiences with the AV8? How do they compare to the "high-end" drivers, like the Accuton C2-92/6 or the Dynaudio 24W-75? Anyone else have drivers to recommend?
I'm looking for a useable frequency range from 80Hz-1kHz in a sealed box.

Thanks, Won