That driver looks to be mixed bag:1.) Very good efficiency;
2.) Good power handling capacity;
3.) Ragged high end response (not unusual for extended range drivers);
4.) Severe roll off above 15,000 Hz (to be expected from a large driver);
5.) Severe off axis roll off of higher frequencies (again to be expected given the driver size);
6.) Bass roll off starts around 150 Hz (quite unexpected from a 12 inch driver, and this in a cabinet!);
7.) Specified bass response is severely overstated (this driver needs a sub that could use a smaller driver!);
8.) With Qt = 0.43 this could be a good candidate for bass reflex, transmission line, TWQP, open/infinite baffle.
Don't know the price (or recognize the brand) but a number of 4 - 8 inch diamter Fostex drivers that provide more extended frequency response with less beaming, but somewhat less efficient.