I learned to dive in Cozumel, where the water is warm and clear. I figured I'd be a vacation diver....but when we were diving there, I realized I loved it and didn't want to do it only once a year. So when we got back home in socal, we went diving in the 55 degree water that had a surf entry and 5-10 feet of visibility. For some reason, I never had any issue transitioning from the tropical, clear water of Cozumel, to the murky, cold water of socal....
I understand the sentiment in training in the conditions you plan to dive in, but I didn't have any issue transitioning from great conditions to okay conditions. But at the same time, I would NEVER think it's okay for me to go from where I am to ice diving without getting proper training.