What do you think are the relative advantages or disadvantages of the horns you've built/modeled with "cells" vs "vanes" vs "open mouth" styles?
Great question. I've been "pondering" about the very same thing. Below are my impressions based on listening to the 3D printed horns.
1) Multicellular horns do everything well. Very polite and competent. Have the widest beaming.
2) Multi-vanes. Due to the physical fact that the vanes connect the top and the bottom of the horn walls, they are more much more rigid than the open mouths. IMHO, they come closest to the classic WE horns sound. I prefer such designs.
3) Open mouths. Even with 3D printed horns, they have a small amount of "ringing" possibly due to the lack of internal bracings of the multicellular or multi-vanes designs.
4) 90 degree bends are wicked. They do add a nice and interesting "flavor" to the sounds trading off efficiencies and some loss of the higher frequencies for 3D printed horns. Do not know the effects if different horn materials are used such as cast aluminum or concrete.
5) IMHO, different horn designs produce different sounds. But, a horn by itself does not make a system. The key is to understand the horn characteristics well enough to pair with a suitable woofer to make a system.
To be clear, these are my personal opinions. Do not take them as facts.