My experience: I have had a Dell XPS 13 since 2007. I had to replace the power supply last year (so after 5 years) because the connector had been broken (probably putting a foot over or pushing it with a chair). The way the connector broke made a shortcircuit in the motherboard and the laptop died but fortunately I still had an extended NBD warranty cover so they changed the mobo for free. I had used this warranty also in the past to change the display when it had some problem a couple of years before. The warranty didnt cover the powersupply (nor the various batteries I had to change in these 6 years, i think one every couple of years, the last one was a chinese compatible that was even bad and lasted probably 6 months).

In my previous company we had I think 5-6 XPS and 10 Latitude laptops and We had (i think) 1 motherboard problem, 1 or 2 power supply problems and dozens of batteries changed. We had also 70 or more desktops, very few failures.

I generally think Dell machines are good, but something has to be done for batteries (not only Dell ones...)