My experience is that the Model T Signatures and the active versions are very linear and neutral sounding. The upper registers are in very good balance with the mids, and about as open as you are likely to come across with dynamic drivers requiring crossovers. The active variants are equally well balanced, but audibly more revealing and dynamic across the speakers' bandwidth.
I started with passive Model T Sigs, and then upgraded to the Bax and the actives. I have a listening space that is larger than average, which does double duty as a theatre. 2 channel music listening is roughly 80% of the use of the room, which is 25' deep by 18' wide with a 10' ceiling. I use moderate aborbing panels spaced along the side walls, one similar panel centered on the rear wall, and one moderately absorptive "cloud" on the ceiling, between the speaker locations and the primary listening seat. The panels are only 1" thick so that they primarily affect only first reflections at higher frequencies. I've intentionally avoided absorption at lower frequencies, such that the room remains reasonably "live". The front plane of the speakers is roughly 40" from the rear wall. The preferred seating position is roughly 12' from the speakers, with the front L & R speakers roughly 10" apart.
The speakers do not perceptually roll off higher frequencies, but I can see how a room with excessive damping, particular if it absorbs down into the upper mids, could create such an impression. Listening to better mixed recordings, I hear a great balance between tonality, dynamics, range even into relatively low frequencies, and soundstage.
The off axis "sound power" really seems to contribute to the adaptability of the speakers in different positions and rooms. I do find that having the speakers well away from the wall behind really opens things up. The other consideration is toe in. IMO, too much toe in makes for irregularities in perceived depth across the width of the "stage", and pushes vocals and mid-heavy instruments back. Many users toe their speakers in too much, depending on their listening space, of course. Less toe in will often create the impression of sounds both in front of and behind the plane of the speakers.
YMMV, but try adjusting toe in.
Brian