I'll start by acknowledging that I am likely in the minority with this opinion: I miss the Mach X 2. Despite all of its haters, I adored that shoe. It felt light, springy, and energetic in a way that the next iteration lacks in my experience. I think that's due to the updates that Hoka made to the shoe's structure this time around. They changed the upper material from creel mesh to warp knit, which does make for a more durable and protective design, but reduces breathability while adding a noticeable amount of weight and bulk. Hoka also redesigned the heel collar to offer a more padding against the Achilles. The Mach X 2 had become notorious for causing bloody ankles, so I'm sure that most people welcome this change especially... but not me. I never experienced a single hot spot from the collar on the Mach X 2 and loved the breezy, barely-there feel of the minimalist upper construction. The updates increased the shoe's weight from 8oz to 8.6oz in my size, which doesn't seem like it would make much of a difference in theory, but did for me in practice. It felt heavier, clunkier, and less energetic in a side-by-side comparison between the X 2 and X 3 models. More on that later, but my bottom line here is that the structural updates might not be worth their cost in weight for all runners.
It's also worth noting the key factors that didn't change. The X 3 uses the same midsole construction as its predecessor—dual-density foam with a PEBA top layer—and the same Pebax plate. Don't get me wrong, I loved this aspect of the Mach X 2, so I'm not entirely bummed that we get it again in the X 3. But it would have been nice to see some upgrades in this part of the shoe as well, especially because the additional weight and bulk of the new upper construction seems to dampen the energy return of the midsole. Taking advantage of new shoe technologies here might have helped negate the tradeoff.
