Dunno, it seems to overcompensatethe level but still drops off top end early when compared to real world. I will stick to using the constant directivity assumption and estimate an octave or more extension.I think directionality is only one factor affecting high frequency response, and Hornresp still uses mathematics of "mass rolloff", which cannot be acurate whilever a speaker is NOT a flat plane rigid piston.
Still cut-and-measure for me.
Cheers