From my hunting days, I learned the only durable, breathable and waterproof membrane is GoreTex. I've been hoping for years someone would make a full size MX boot with GoreTex. So stoked it has finally happened, and by the best MX boot maker out there, Gaerne (at least in my experience).
The folks at Atomic had the boots in my size in stock and shipped them out quickly. They are always good to work with.
The Goretex liner comes up 3/4 of the way to the top of the boot. I had to step in about 15" of water with them last weekend, and they worked as advertised. Dry feet. And I have no worries they will stay waterproof for years to come.