I've been using a pair of Synchrony Ones for about six months. My *purely subjective* opinions are that their upper midrange has a bit of color which leans toward brightness, and that their highs are a bit slow and leave a little bit to be desired in terms of precise imaging.
It is also my *purely subjective* opinion that the Synchrony Ones' bass and low midrange are first rate. The integration between the Synchrony Ones and my servo subwoofer produces a seamless "wall of bass" with world class directionalty, tonality, and pace.
Of course I am aware that the above may be minority opinions. I am also aware that my listening environment and associated equipment affect my opinions. Nonetheless, my advice is to audition the Synchrony Ones with a variety of upper octave artists before making a commitment.