I've had the Lumia 950 XL for about a week now. I was a bit concerned about overheating given the past history of the Qualcomm Snapdragon 810, but I did not have any problem until today. I was taking photos and shooting short two- or three-minute videos when the phone started becoming hotter and hotter. In the middle of a video I got an "overheating" alert on the screen and the phone rebooted on its own. After that it kept rebooting every 5 or ten minutes for a few times before stabilizing again. Now it's back to normal, but if taking a few videos is enough to bring the 950 XL down on its knees, it's definitely a show-stopper.