but I do know that this arrangement does not have the dreaded horn "shout" or any other colorations that to my ears identify it as a horn.
IME this is the result of using the wrong kind of amplifier on the horn, rather than something inherent in the horn itself. Most older horn designs have crossovers that are not designed to work with amplifiers with lots of negative feedback (low output impedance); this results in crossover errors when such amplifiers are used. The result is that the horn may be playing information out of its proper passband! *That* is where that honky shouty horn reputation comes from. for more info see:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php