My experience with Dakines has been good with their higher end products like the current Scout gloves. I have had bad experience with their lower end products which seem to fall apart quickly and have poorer breathability.
There are some nice features with this mitten that include: -idiot leashes -very nice material for glove liner -goggle squeegy -chamois on thumb for wiping nose -zippered access to the back of the mitten for heat pack or for some breathing
The liner is the same used in the Dakine Scout glove which I have. It is made from some nice material like Polartec power stretch or similar. It's better than a typical liner, and seems to wick moisture better, is thick, and stays comfortable longer.
Regardless of the liner, or insulation, or goretex, I think the key to a gloves warmth is how well it breathes. I have to take the gloves off on the ride up to help extend how long till the insides and the liner get damp. Once damp they will be cold. The zippered access to the back of the mitt is nice because you can get some extra breathing, but the zipper is small and hard to open.
With a heat pack in there these will definitely be warm. Relative scale is personal. I have used them in single digits without heat packs so far. I prefer gloves when possible for th extra dexterity in strapping in my bindings.
The thumb seems a little bit on the long side so decreases dexterity.