i want to squeeze every drop out of this driver to see what it will do and so i'll know whether or not to keep it or look into a new project.
There isn't that much more to squeeze. You're getting pretty close to max driver levels up until the amp shuts down. Remember that the power to SPL level is logarithmic. The next notch up is a 1600w amp. That much power is crazy in this application. What you need is more surface area, I.E. drivers, and an amp that can handle your listening habits. "I"
wouldn't run the Behringer amps bridged at these duty levels. (bridged into a 4ohm driver at +100db levels) Now if you are still planing on "dual somethings" the EP2500 will run at 4ohm a channel all day at 750w. I would decide what I was going to do before buying anymore equipment. That way you don't end up having to buy a third amp later on.
Check out this site for an SPL calculator, your driver is around 87-89db sensitive SPL Calc
It makes more sense to buy more drivers to get an extra ~3db per than to get +3000w amps to get the same output, if you have the room. Especially since the driver cannot handle those power levels anyway.
There is no replacement for displacement.
Two 12's with +700w a piece might get you there(~106db at your seat). I'm pretty sure three would(~109db). Four would have the beginnings of overkill(~112db), just the beginnings though.