iPad #3 has no dead pixels (well, maybe some stuck or dust under the screen, but not a big deal). There are already spots of blb along the edge, more so than on my previous iPads, but I could live with this as well. What I can't accept is this one has backlight flickering. The best way to demo this is to check mail, then while the little icon in the bottom-left corner is spinning the backlight flickers noticeably. My iPad is set at the lowest brightness level and light sensor is disabled (these are the settings I always use to slow down blb).
Will have to exchange again. Here's hoping iPad #4 is worry free.
To recap my iPad 1 64GB 3G experience:
iPad #1: No dead pixels, minimal blb along edge, but two growing spots of bleeding in noticeable areas of the screen. These appeared about 10 months after purchase.
iPad #2: cluster of ~8 dead pixels
iPad #3: backlight flicker (and more than usual blb along edge, but flicker is the biggest problem here)
Unfortunately I can't wait this out since there will never be another batch of iPad 1; otherwise I would wait a month or two before exchanging with Apple (except for the screen flicker, I wouldn't be able to live with that for two months).
-Update-
So today my rep explained that the first iPad replacement I got (iPad #2) had refurbished internal parts but new outside parts. The second iPad replacement (iPad #3, which she got for me last night) was completely new. She could tell refurbished from new by looking up the serial. I requested a new one for iPad #4 but they were out of stock. They are having one shipped to them and should arrive either tomorrow or Friday. In the mean time I hold on to iPad #3 and picked up AppleCare so that I can get another year of this awesome coverage. She said to register AppleCare to my current defective iPad, and it will automatically switch to the new one when I swap tomorrow/Friday.