So I've researched box rise, aka impedance rise.
There are numerous people that back up what your saying. I.e putting more then rated power on a woofer.
However almost every forum I've read about it unanimously agrees most people shouldnt even worry about Impedence rise.
I'm also finding people say if you want to put 3k to a subwoofer, then get a 3k rms subwoofer, not a 1.5k one.