The Mach X 3 is HOKA's plated trainer: a PEBA top layer and a firmer base sandwich a Pebax plate, with a speed-tuned MetaRocker rolling it all forward. This generation's changes are comfort ones — a softer tongue, more breathability, a woven upper — because the ride was already the selling point.
It suits you for up-tempo training miles: speedwork and long efforts in something more protective and more durable than the carbon racers it imitates, which is the whole super-trainer bargain.
It is not light at about 289 g, and its Pebax plate is deliberately gentler than a carbon one — a race-day HOKA is a Rocket or a Cielo. It also crossed to $190 this generation, so the "budget alternative" framing has quietly stopped being about the price.