Thanks for a thorough reply (as always)!

A third "kind"(?) of flare is the so-called Constant Directivity horns. At least from a distance they "look" quite similar to the purely exponential horns, although I understand that they are somewhat different mathematicially.

Do you also find that CD-horns are almost similar in SOUND compared to purely exponential and round tractrix horns, or do CD-horns have different sound characteristics?

Thanks again!

Regards
Peter