End of the day think what you want and dont bother trying to get the laptop fixed. Its not software and I can prove that and Apple has not been forthcoming with any sort of fix.
You need to get a repair / replacement, nothing else will fix your problem. Just because you applied an unrelated firmware fix and have not noticed the flicker doesnt means it was fixed, its a random happening and cant be predicted, but you will see it again.
Buy hey, with my replacement that has had 0 issues over the last few months compared to my old one which did have the issues (on exactly same setup) Im happy, feel free to ignore advice and hope for a software fix to what is definitely a hardware issue.
This isnt to say that every screen issue on everybodys laptop is the same, just for what is described in this topic.
The iMac issue is unrelated to this, completely different hardware (ati compared to nvidia and a whole different board design). Those issues, while similar, seem to be software related, although that too is questionable)