The X3s are some of the most natural sounding speakers I’ve encountered if they are setup well and driven with decent (not necessarily expensive or esoteric) equipment. Both their midrange and treble is more refined than you’ll get from any of the popular BBC-derivative brands but more detailed as well. In that sense they are true “high end” and “HiFi.”
If one determines they are “peaky” or unrefined they should revisit their sources and amplification. Many popular speakers with a rep for being non-fatiguing sound like distortion machines relative to the Borresen X series.