The zipfits for me are great in the cuff area. Their edge to edge quickness due to this cuff transmission was really quite amazing. Ironically, the feature I liked most in the store has turned out to be one of the worst. That's the tongue. In the store I thought it was great- it contacted across the whole shin, not just the middle like most cuffs, so in flexing forward it didn't have that hard spot in the midle of the shin. It almost felt like there was no tongue. Wow, this is great!
Well in skiing it often does feel like there is no tongue! This is because the tongue is so wimpy. Looking at it closely it's probably the softest tongue I've ever had in a boot- it bends forward quite easily. The section above the cuff bends forward or rolls over the cuff way too easily. In my previous liners I got rid of a Nordica foam tongue I used to have because it was too stiff and went back to the stock Dobermann tongue which turned out much better. This zipfit tongue is so soft though it becomes a problem when you run into clumps of snow or are skiing difficult terrain. (As in Alta in Jan.- the first day on the zipfits which was a little bit of a nightmare.)
What annoys me is I violated the "never get major boot stuff while away on vacation" motto. I'd made this mistake before at Taos with a foam liner. With these zipfits I ended up having to get them stretched back here. I got some frostbite on the tip of my big toes and will loose one nail mainly because they were a bit short.
I think if you don't need to fill up volume they probably could be great (as many people attest). In my case I think I needed to fill a little more volume than they're capable of. The tongue issue though will really depend on the boot it's going in and how the tongue is supported by the plastic in front. I notice in mine there's a bit of a gap in the middle between the tongue and the plastic. Still, where the tongue sticks above the cuff, it just rolls over with no strength at all.
If I was skiing out west, I'd would immediately have to solve the tongue problem or get rid of these liners. As it is here I can get away with solving the problem a bit more slowly. I suppose one test of a product is if there was a "money back gurantee" would you return it? In this case yes, I would. They do some things great, but overall I don't find it worth it. I'd use the money to try a different path- foam which isn't smooth sailing either but...