Loved these! They're a good, comfortable platform. I initially purchased the infamous Shaker 100 in more rigid leather, and they didn't fit my legs at all. I have proportionate calves, but around the most muscled part they're roughly 16 inches around. That makes it hard to wear Demonia in tall styles, unfortunately. These are made with vegan leather, which makes them stretch, and that makes a world of difference!
Straight out of the box, I only have half an inch at the top where the boot shaft is tight. After a few try-ons, I can feel the lip loosening up, so it's clear that over time the boot will adjust to fit my leg perfectly. I usually fall in the 9/10 size category, and I can go between sizes fairly easily. I ordered a 10 and it's a pretty close fit for me without socks. There's a slight gap between the boot and the shaft/heel, but I expect that when the shaft is pretty tight to the leg.
I'd recommend sizing up if you're a half size AND you have a slightly larger calf size. Know that the boots will stretch some, so if you struggle with the zip near the top, you'll likely be able to see that change over time.