A bit late chiming in here, but I just defeated the bi-wire provision on my speakers, and to me the sound is noticeably smoother, fuller, and more coherent. I've only listened to three record sides since doing it, so it could just be the psychoacoustic effect by which "changed" is oft initially perceived as "improved". We'll see.
I realize that my brief description of the 'new' sound also could be read as evidence of rolled off treble, but I don't think that's the case here. My system at times shows some glare or brightness, but I think this is more in the mid to upper midrange than the treble, which could put it somewhere in the crossover range of my speakers (somewhere around 2.5-3 kHz). It seems reasonable that defeating the speakers' bi-wire capability could affect this frequency region.
I realize that my brief description of the 'new' sound also could be read as evidence of rolled off treble, but I don't think that's the case here. My system at times shows some glare or brightness, but I think this is more in the mid to upper midrange than the treble, which could put it somewhere in the crossover range of my speakers (somewhere around 2.5-3 kHz). It seems reasonable that defeating the speakers' bi-wire capability could affect this frequency region.