I go barefoot year round. I would definatley take off the shoes, and I would reccomend year round
. Lots of horses do just fine doing the stuff so called hard on their hooves, jumping, dressage, uneven trail riding just fine without shoes- and often better! If you ride your horse on rocky ground, and they have soft feet, I would recommend easyboots, or a some other hoof boot. They protect the hoof from the ground, and isnt as limiting to the hoof as shoes are. And, with about after two trimmings, you will start saving money (if you by hoof boots). Great article: http://www.horsetalk.co.nz/health/ik-barefoot.shtml
Oh, and snow doesnt really compact in barefoot hooves!