I have a new XPS 13. It's impeccably built, you can use it comfortably on an airplane, and it runs Linux with no issues. But I wouldn't use it for daily development. The 13 inch screen just doesn't have enough real estate, and it often feels like it's struggling to drive the 4k screen whenever I try to switch applications.
If you don't mind something heavy, check out the new Thinkpad P50 or P70. They have actual desktop-level performance, terrific screens (matte, color corrected 4k IPS!) and the new NVMe SSDs. I do most of my daily development on a P70, and increasingly just lug it along when I travel even though travel was the reason I bought the XPS 13.
I don't own a P50 or P70, but one complaint I would have is that having a numpad on laptop ends up putting your hands in an awkward position. I almost never use the numpad anymore since I can touch-type on the number row and my main laptop (a Mac) doesn't have one.
If you don't mind something heavy, check out the new Thinkpad P50 or P70. They have actual desktop-level performance, terrific screens (matte, color corrected 4k IPS!) and the new NVMe SSDs. I do most of my daily development on a P70, and increasingly just lug it along when I travel even though travel was the reason I bought the XPS 13.