Yes, I've tried it on ice and snow. When going straight, the traction control is so good that you don't even know it's there aside from the lack of acceleration. I can put my 360hp RWD car on an icy road and floor it from a stop, and nothing happens besides slowly increasing speed.
Then back end will break loose if you floor it in a turn, but just don't do that.
That cornering case is the precise case I don't want a RWD car. "Just don't do that" is a really poor attitude to take, especially when you can't tell at what point the rear end will break loose.
I'm past the point in my life where I want the excitement of "will I recover this before I hit the ditch?"
Cars have tons of "just don't do that" failure modes. For example, flooring it while at a red light. It's not inherently bad advice.
IMO there's a huge difference between a car where "the slightest bit too much pressure" causes the rear end to break loose, and one where the rear end will break loose but only if you really abuse the accelerator. The Model S is in the latter category, and the Model 3 will probably be as well. As long as you drive like a sane person, it's fine.