Never tried ice baths but I did make some experiences with cold. Here are my winter experiences (where I lived it got to 0º celsius)
first time took a cold shower, I realized I was crouching when I recovered a little bit of my senses after the initial shock. It was obvious then and there that if I could remain conscious during this there would be massive benefits.
Sometimes I would also meditate semi naked (wearing only underwear). After a bit of practice I felt no pain being in the cold and began sweating during meditations.
The worst I've ever done was meditating in the rain. The fucking wind made it terrible. Thought I would die for sure but it wasn't half bad when I got up and started walking around. Did this only once but maybe I should try it again.
Isn't this thread a violation of rule 2