I wrote a review when I first got my pair but it seems to have disappeared.
Anyway, love the boot, nice traction, works well with semi-automatic crampons, and...not too narrow! I see reviews regarding Kayland with narrow feet and Kayland with wide feet. I have wide-ish feet (D width), small feet (6 womens), but most importantly is that my feet are wide across the toe area (not much tapering, more like duck or square-ish) so finding boots that are wide in the toe-box is quite problematic (original Keens were made for my foot, Chaco sandals as well). These Kaylands work quite well for me in the toe-box area. It could be that the asymmetric lacing allows for fitting wide and narrow feet. It could also be that for me, a narrow boot is one that tapers aggressively from the wide part of the foot to the toe (La Sportiva); so, while these might be "narrow" across the ball of the foot, the toe-box taper is mild.
Can't really comment on the sole stiffness. There is a rocker sole and that works well. I think most small sizes have stiffer soles compared to larger sizes.
Of course, these impressions are for the small sizes. Larger sizes may well be narrower.