The correction isn't much of a issue just the narrow bandwidth necessitates multiple conicals to cover range that other flares handle. Still I find the imaging to be better the sense of loudspeaker disappearing presenting a sound field is also bettered over other types I've used.
Conical horns whos using them and your opinion
On performance of such. I have been experimenting for 2 years with conical. I have also used most all flares and horn types about. I do feel there is something special about the conical performance. They are a pain to build and integrate due to size the ranges are narrow but they do disappear when in use image better than other flares wave guides I've used. Not sure I'm sold on it yet but seems to me a good route to explore. Wonder what other users of conical horns could add.