I had a little long term experience with the 3rd gens having owned a couple of '03s and the '05. I did not opt for any extended warranty on my '06. I am plenty confident that I wont need it and see no need to line the dealers pocket with a money grab like that. They mark those things up to the moon to squeeze extra bucks from the deal. In reality the chances that you will have a failure major enough to have the warranty "pay for itself" are pretty slim. If you have an auto trans and pull a lot, you may be able to justify it. Also if you plan to bomb the truck at some point you may very well void the warranty you just dropped $2000 on. Lots to consider, don't let the F&I guy convince you that you need it, he is making big bucks on junk like that, and GAP insurance, and paint protectants and window etching for "security". All a bunch of scams in my book.
Now on a used vehicle, especially one you can tie certain potential failures to due to others experiences, I have bought and needed extended warranties. Once on an Isuzu Trooper (blown headgasket covered) and once on a Honda Accord (manual trans failure). On these trucks... . no thanks.