The Hierro is New Balance's cushioned trail shoe rather than its nimble one. Dual-density Fresh Foam X sits under a Vibram outsole with 6 mm lugs, the drop is 4 mm, and there is enough material underfoot to keep a long day on rock from taking your legs apart.
It suits you if your trails are long rather than technical, and if you would rather float over rough ground than read it. It carries an ultra distance comfortably, which is most of the point of it.
It is not light and it is not precise. At 310 g it is a lot of shoe for a hill session, those lugs are noisy and wasteful on the tarmac between trailheads, and anyone who wants ground feel on a steep technical descent should look at something thinner.