They're probably all LG panels under the hood[1]. Different resellers have different pixel policies, and they can be a bit hard to keep track of.
On these size screens, Apple won't replace <11 dark (dead-looking) or <9 light (stuck-looking) pixels. HP's policy is about half that. Lenovo is like 4 or something. Some of the other manufacturers have even more complex policies which depend on the position of the stuck/dead pixel.
And in practice, if you complain well enough in the store, Apple may replace for you even if you're under the line.
[1] When I say "they", I mean these 27" IPS panels, whether they're from Apple, Dell, HP, or some random Korean company.
The problem with Dells return policy - at least according to much i've read about it on the interwebs - is that they indeed have a pretty liberal policy regarding returns, but you seem to be almost guaranteed to receive an already returned (i.e. not new) display...
I've found this out because i wanted to swap out my U2711 which has some issues when it's warm in the room - it might just go blank for a few seconds and then go back on again...
However since that is quite seldom (sometimes once a week, sometimes 3-4 times in an hour and then returns to normal) i've refrained from returning it cause one could get an even worse model - or so i've read..
For what it's worth, Apple replaced my Retina iPad that had a single stuck pixel, and it was only noticeable on a dark background in a dark room. While it's a small screen, the number of pixels is about the same as on the 27" Cinema display.
What their official policies say and what they actually do are pretty different, it seems.
I never had issues with an Apple big screen but they replaced my 13" MBA for a single dead pixel. And the Apple Genius was very surprised as he never saw faults on those.
On these size screens, Apple won't replace <11 dark (dead-looking) or <9 light (stuck-looking) pixels. HP's policy is about half that. Lenovo is like 4 or something. Some of the other manufacturers have even more complex policies which depend on the position of the stuck/dead pixel.
And in practice, if you complain well enough in the store, Apple may replace for you even if you're under the line.
[1] When I say "they", I mean these 27" IPS panels, whether they're from Apple, Dell, HP, or some random Korean company.