If you're busy, it's easy to stay warm. It's when you stop, and you're all sweaty that you get cold.
I grew up here in Minnesota wearing LaCrosse rubber boots, but even they leaked anywhere there was stitching, like around the laces in front. We would all put our feet in an empty bread bag before putting the boot on. That helped keep the moisture out for a while, but it also kept your sweat in, making your socks wet anyway, and making your feet freeze once they were wet. It was still a good idea to take the insulated liners out and dry them at night on the radiator or heat duct.
If I could afford all leather winter boots today, I'm not sure I would choose them. I think there may be something to the new materials about letting your perspiration wick away from your skin, keeping it dry, and thus warmer. Wool socks in a leather boot should also work, but I'm not sure as effectively as modern materials.
Nowdays, the liners don't even come out of most boots for drying. The Thinsulate is sewn right in. The nylon materials and waterproof layer material the manufacturers have at their disposal, is truly awesome. I too was skeptical of not being able to find a decent pair of warm boots that weren't fabric, but I hope some others here will attest. Many fabric boots that say 100% waterproof can be trusted to be waterproof today. I should point out that I probably won't buy any warm boots that don't use
Gore-Tex as the waterproof membrane, until I hear of one being equal or better.
I have a couple pairs of Irish Setter boots myself, and they stay dry, keeping my feet warm up to 3 hours sitting still in sub zero weather.
My all leather, warm weather boots are Red Wing though, and if I lace them tight, I can walk through water up to my knees for a short stretch and they don't leak, although my feet sweat terribly in them. That makes them really cold when the temps drop.
One thing I'd keep in mind is if it's REALLY cold, like 10F or colder, it's not raining. Everything stays much drier, making it easier to stay warm. Frozen snow doesn't get anything wet. The worst enemy is your own sweat. If you have to walk through a stream or something, DON'T, unless you're pretty near to a place to get warm. You could fall in, and once you're so cold your limbs don't work, you're done. Obviously I've never been there, but felt way too close a couple times.
These are probably warm, but getting spendy.