More breathable than Windstopper
I got my Kepler to replace an old Dragon. Since the Kepler is ostensibly the replacement for the the Dragon, I thought I might share my impressions on the Kepler in comparison to the old jacket.
The Kepler seems to be a hard shell with a soft touch. On the MHW website, you can find this jacket in the shell section, described as a softshell. While that seems confusing (in no small part due to the fact that the site has a separate section for softshells where the Kepler is NOT located), it makes a lot of sense once you get your hands on it. It definitely has a soft feel both on the inside and on the face fabric, but the Dry.Q Elite membrane itself is rather stiff and a bit crinkly. The jacket overall is a lot softer than any hard shell, but it definitely is a shell. It's a lot more shell-like than the outgoing Dragon, as the face fabric feels more solid but the interior is actually softer against bare skin.
The fit is basically what I expected based on my experience with the Dragon and other MHW alpine jackets. The length in the back is long enough for bike riding. One thing that keeps coming up in reviews is the arm width/length. I definitely could have gone for narrower arm holes (where sleeves meet chest) because the jacket does lift up quite a bit when I lift my arms, but otherwise, the arms are perfect. I'm a pretty big-armed guy and the sleeves are plenty wide and long. I think when people talk about the lack of proper arm length, they mean when using the thumb loops. The butter jersey cuffs are recessed pretty far behind the wrist, so the thumb loops seem like an afterthought. The arms feel way too short when I use the thumb loops. When I forgo the loops and use the butter jersey cuffs as cuffs, the arms feel fine (and my wrists are ridiculously comfortable). Overall, I would say the fit and feel of the Kepler is an improvement over the Dragon.
It's waterproof. There is no doubt about that. My old Dragon was clearly not waterproof. It didn't even have a watertight main zipper. It did take a pretty serious rain to wet out the Dragon, but the Kepler is waterproof in all rains. The 40,000 mm waterproof rating means you could put a 130(!) foot column of water on the shoulder and not a drop would get through.
The Kepler is also significantly more breathable than the outgoing Dragon, which used Windstopper instead of a waterproof membrane. The Dragon, while more breathable than any waterproof-breathable I had tested up until now, still developed the microclimate problem common in shells. There wasn't any airflow so my body heat and sweat made the inside of my Dragon much like a tropical jungle. This happened to an even greater extent in my various waterproof-breathables. But in the Kepler (I suppose due to the air permeability of Dry.Q Elite) no microclimate develops. I took it on a serious bike ride on a foggy rainy day, and the only place I felt moist was under my backpack. My head was dry, my chest was dry, and my armpits(!) were dry. This crazy breathability and the lack of a microclimate means two things: 1) Overheating and the fatigue that comes with it are non-existent. You really can go harder longer in Dry.Q Elite. 2) Body heat and sweat escape so quickly that you might want an extra layer compared to a Gore Tex shell. It completely blocks the wind, but that plastic bag effect you probably are used to in waterproof-breathables just isn't there.
Overall, the Kepler is an outstanding piece that delivers on all its promises. There's not much to complain about, and it's all minor stuff. It's definitely a massive step forward from the Dragon and the status quo.