Sloped baffle

I should have stated, "PART of the reason for a sloped baffle..." There is the time domain as well.

Sometimes sloped baffles are cosmetic only. My understanding for 1st order crossover speakers is the broad frequency overlap between drivers, requires a sloped baffle to keep the drivers on a single axis. When off axis the shared frequencies between drivers will cause cancellations/nulls depending on the distance.

I believe it. Hales uses fourth order crossover. It is of course not time coincident as one can see from the step response. You could speculate that part of the intent is to visually differentiate the transcendence from the revelation line, which it does.