I think the original intent of the Smith horn is to provide a wide and diffused HF dispersion for use in a mono-single speaker setup. In modern multi-speaker systems, there's less of a need for such wide dispersion, so 90 or 60 degrees can make sense. Sensitivity may also increase.I did noticed that when I switched from my 2380A horns (90x40) to the smiths, I loss a few dBs in sensitivity and had to adjust the L-pad. No big deal as most compression drivers have over 10dB advantage over the woofer, so there's lots of room to play with in the L-pad.