I ve heard the usual magnepan , martin logan , audiostatic ,but not their large topmodels .
Horns : Blumenhofer big 60 K model , westminster big 40 K model , avantgarde not the big model , zingali , klipsch, JBL various studio/pa designs and some more i forgot .
See i only remember gear i like, from horns not even one i liked , more or less acceptable was may be the big klipsch , i think if you would do a independant Frequency response check on them , you d get a hart attack with most lol .
Completely coloured loudspeakers tailored to certain kinds of music , but this is off course my only dum opinion.
There was one active PA loudspeaker i liked though it was in an outside environment open space at a carshow and i thought it was quit nice , no audiophile thing
I don't like any of those horns either. I would take cones over them. Which westminster, btw - you are not referring to Tannoy Westminster?