RE: Dell XPS 13 2015 and Samsung 950 PRO m2 Upgrade
Now that's interesting, because the 951 and the 941 are both PCIe parts according to the Amazon product pages with 4-lane connectivity. I've since done more research and it looks like PCIe parts are compatible with the XPS 13, but NVMe is not based on my first-hand experience. :-)
I just went through a painful 20 minute call with Dell's XPS support team - the one they call "premium". It was absolutely horrible. The tech knew NOTHING and I kept asking to speak to a level 2 tech or his manager, but he wouldn't transfer me.
95% of the time when I call Dell I feel disappointed. :-(