Klipsch uses non-aggressive horns? Huh? Only the humble Forte uses a tractrix flare. IME (I have owned K-horns and LaScala) these speakers have far more audible horn coloration than the AGs.
Conical mid horns with proper (thick, non-resonant) construction and the bit of necessary EQ have virtually no horn coloration - none.
But there's still a substantial downside - no mid horn can go lower than a couple hundred cycles at the very best and so you are always going to have an xover in a pretty critical region. Not that it can't be made perhaps close to inaudible, or at least non-objectionable. But this and other trade-offs will always remain.
Conical mid horns with proper (thick, non-resonant) construction and the bit of necessary EQ have virtually no horn coloration - none.
But there's still a substantial downside - no mid horn can go lower than a couple hundred cycles at the very best and so you are always going to have an xover in a pretty critical region. Not that it can't be made perhaps close to inaudible, or at least non-objectionable. But this and other trade-offs will always remain.