Dell
Unfortunately, Dell didn’t take the time to answer our questions. We found their warranty conditions on their website. So much for our questions.
Dell didn’t respond, but our research on their site (not an easy task as we couldn’t find it in specifications or screen info) suggests that they have the same policy as two years ago.
In really digging you find on a Dell.com support page :
During the manufacturing process, it is not uncommon for one or more pixels to be fixed in an unchanging state. The visible result is a fixed pixel that appears as an extremely tiny dark or bright discolored spot.
In almost every case, these fixed pixels are hard to notice and do not detract from the display quality or usability. A display with 1 to 5 fixed pixels is within the industry standards, and is therefore considered an acceptable display. LCD/Plasma screens that do not meet this industry standard are rarely passed on after manufacturing.
This is summed up in the following official table:

On the one hand, the guidelines are advantageous compared to the ISO for larger screens. On the other hand, this makes us a little uneasy when we buy an expensive screen, which Dell does happily offer.
Actually, we know from experience that Dell’s warranty service is quite understanding. We know of several examples where clients exchanged screens right after they received them after finding backlighting or dead pixel defects.
It’s just too bad Dell doesn’t offer a more interesting official warranty.