Hi Sean I see I got your attention. The conversation seems to have become a bit polarized. I don't think it's a question of listening directly on axis, or significantly off axis. I suspect that most people (myself included) listen somewhat off axis horizontally, and that in terms of degrees it's someplace in the 10-20 degree range at a normal listening distance. All of the speakers I have designed for Jim measure very similarly on axis and 15 degrees off axis--certainly up to 10 kHz. I am confident that if the response were allowed to rise starting at 7 or 8 kHz, the rise would still be evident 15 degrees off axis. I haven't heard any of your crossovers, but I do have extensive experience with those of an eletrical engineer who deliberately builds a rising resposne into the on-axis response. The crossovers are beautifully integrated, but the resulting sound is always bright, on or off axis.
Plus, the on-axis sound will be reflected, particularly off of drywall, and therefore will figure in the overall response even if you're listening off axis. All of this aside, it does look like your crossover fixes a midtreble peak that might be woofer breakup (?). If so, then it's quite possible that your crossover is a significant improvement, and that most people would hear the improvement as a less bright and irritating sound irrespective of the profile has been chosen for the response further up.