Doctor, you sometimes make my eyes glaze over. Reflections and direct sound . . . that sounds like you've been reading Bose 901 literature.
As far as power response, I'm afraid I don't follow what you're saying. R U saying the dB level coming out of the speakers or R U saying the amount of power the amps are kicking out or what ??????????????? I don't know how a room has a power response ???????????????
I am glad that you agree that real life situations with music do not have constant directivity. I am thinking back to every time I have heard a band play. I am thinking back to every person I talked to during and after. I am sure that NO ONE EVER complained that it would have sounded better if the speakers had had Constant Directivity. I rest my case.