I haven’t used the XPS 13 personally but my experience and all my friends’ experience with the XPS lineup is that despite their build quality, they’re quite prone to failure. On my 15, the keyboard failed multiple times, as well as one of the fans and eventually one thunderbolt port, all within a span of 4 years.
They’re beautiful machines that really should be quality, but in practice for some reason they haven’t lasted for me. On the plus side though, Dell does at least offer service manuals, and lots of parts can be replaced by a user (on the 15 you can easily replace fans, RAM, SSDs, and with some work you can replace the top deck, display, and SD reader).
I’m glad to hear yours have been holding up! Maybe my friends and I were just particularly unlucky.
The service manuals are available direct from Dell. For all the laptop’s faults in my experience, I do appreciate that the SSDs are socketed, as are the RAM sticks on the 15. I do also appreciate that Dell sells replacement batteries (and they aren’t glued in either!) as that’s usually the first part to need a swap.