Most of the midwoofers that come to mind are tuned so that they work best in small vented cabinets having fairly high cutoff. They could be put in a larger cabinet to yield an EBS alignment, but the shelved response resulting from the lack of horn loading in the bass plus additional reduction in bass from an EBS alignment in the vented rear chamber would probably yield too little bass to be really useable. In short, most of the good 12" drivers I'm thinking of are better used as midrange drivers than for something like this.

What we really need is to sweet talk Eminence into a driver tuned like the Alpha 10 but with a powerful motor having a shorting ring. Sort of a Magnum 10 with tuning like the Alpha 10. Eminence loves to be sweet talked like this, especially with a purchase order in hand. We'd need to commit to a hundred units and they'd be happy to make 'em for us. That's something to think about. A 400 watt Magnum 10.