@Sadlsor made an excellent point. It isn't the wool or material that insulates, it is the air that the material traps that keeps you warm.
Boots that are too tight to accommodate thick socks will simply squash the air out of the sock, putting you back where you started. Cold feet.
But no matter what insulation you have, your feet are going to get colder without a heat source. The best heat source is the blood supply. So sitting on a motorbike seat for hours on end isn't going to help the blood to circulate properly. Good circulation and heated seat help to keep toes warm. Get off the bike more frequently and get your muscles and blood working again. Getting feet out of the air flow - put your toes on the footpeg works. I tend to ride 'incorrectly' with my instep on the peg - it gives my long legs a bit more space - but in cold weather I have the ball of my foot on the footpeg for as long as I can.
Parallel note. I've had three heated jackets over the years. The first was a jacket with sleeves. The heated sleeves were not worth having. The jacket reduced the thickness of insulating sleeve I could wear over the heated jacket and my upper arms are in the direct airflow. The heat got whisked away before I felt any benefit. My two sleeveless heated vests have been much better. Better insulation in my sleeves and a heated torso and my arms never feel cold.
@mudduc is right about the body shutting down the extremities first. This happens when the core temperature starts to drop. Keep the core warm, the warm blood will circulate to help keep the hands and feet warm.
But every little helps. I've never felt the need for foot warmers. Hand warmers, yes - I have heated grips. Handlebar muffs are brilliant, but I've never seen a set that will work on the Pan for some reason. And you have to remember not to take your hands out when riding.