Generally negative
At least one user felt the sound lacked clarity and sharpness, and another owner who previously had an ES6 felt that model's sound quality was better than the XS6's.
Frequently criticized
One owner reports that switching from one patch to another takes a moment and the sound cuts off during the change, which they found uncomfortable during live performance and noted doesn't happen on older models from other brands.
Frequently criticized
When combining multiple sounds such as piano and strings in Performance mode, not all layers respond correctly to sustain or release, causing notes to drop out as if the instrument were playing mono instead of poly.
Generally negative
An owner reports that in Performance mode, playing the keyboard on a timbre with drum accompaniment triggers a cymbal sound and resets the accompaniment, unsure if this is a factory bug or a setting left by a previous owner.