Last weekend I drove up north a bit for some real cold weather testing of my Iris+ equiped with Pixhawk. I had to get up early in the morning to catch -30C temperatures which is about as cold as I'm interested in testing. At -30C, my gloved fingers froze after a few minutes. Not quite frostbite, but deep into pain territory.
Spurred on by Leonard's taunts, I also did some snow resistance testing. It passed. I'd say it can handle just about any amount of snow you could reasonably throw at it. :) I simply put electrical tape over the shell vents, and that's it. Throughout the weekend, I had absolutely zero problems related to the low temperatures. -30C is a non-issue for the Pixhawk and ESCs.
I actually haven't had this Iris for long, but so far I'm pretty impressed with it. The out-of-the-box tune was pretty much spot on. It flies extremely smoothly. The only changes I've made were to allow 45° lean angle, and enabling Stab and Acro modes. The camera I was using for on-board is a Sony AS100V on the semi-fixed front mount included with the Iris. The results are not great, heavy jello. I'm not sure if a real GoPro is much better? You can see the effect of the Sony's electronic image stabilization. If you peer through the jello, you can see that the video is actually quite smooth and watchable. I will probably make a damped undermount for the camera.