Late to the party and resurrected one but to stay warm in the cold, exercise so your heart is efficient at moving blood (warmth) through the entire body. Get and stay hydrated so the blood has volume to move heat through the entire body. Garlic pills or baby aspirin to help thin the blood. Always hike cold so the core can release heat, once stopped add high loft layer to hold in the heat. Take a closed cell foam pad to sit and stand on, insulation between any body part and any contact with cold ground or whatever. Do not sit that will constrict blood flow. Lace boots one at a time with full body weight on each foot, this way, the boot will not be too tight once you start moving. There are lacing tricks too to keep laces loose on the foot but snug on the ankle. One is keep laces loose on the foot, at the ankle, use a friction wrap of 4 times then snug laces up the ankle. Trial and error will find the best way. Before you bounce down the trail, rub antiperspirant like Degree all over your feet and between toes to constrict pores to decrease sweating of the feet. I do want 100% wool socks, a blend of 60/40 in my experience is best as you get the performance of both fabrics, minimizing the faults of both.
Layering is good for movement but being static, high loft single piece is what I found best. WT belay, Patagucci DAS, ID Dolomitti type or a parka for dog mushing. The WT Iditarod Parka at one time was considered the warmest parka on the planet, most times it was too warm to wear. When it comes specific brands, they all use the same materials from the same textile manufactures, its the design and construction details of the garment that separates. Before someone wants to argue, perceived value with customers and yes, the retail world knows and uses this or loyalty, and yes some do have rights to specific fabrics through textile mills but its not really that different, its more marketing than performance. I don't know it all but have 17 years in retail and contact with manufactures and was fortunate to have some inside knowledge. I have been to the backcountry with inside and outside sales reps and been invited to the same by them and business seminars. I know what a half half is, this is where a company will stitch up a garment with left side of one fabric and the other side of something different to compare how the fabrics and even design features perform against each other.
Disclaimer, this is worth exactly what anyone paid for it, I try to pass the information and experience I have gained.
Good luck and have fun.