for what its worth, like mike said I have whaled on them and THD is still in single digits at very high spl.
The only folded horn I have is a THT, but its in my living room and not theater room. That being said my ears and guts really prefer this monster. It just seems effortless yet turns my theater seating into a full-on message parlor.
I wish I was more of a numbers guy with data and such but they do more than enough to my ears and room without even really pushing them hard. i have plenty of gain left on the ep4000 but that is only for when i want to whip it out and lay it on the table.