I have some experience here...
Regarding the original post, I've been down this road and here's what I know:
1) Apple has acknowledged that there is a problem. This much is clear from talking to tech support. They are still collecting samples and testing them for the issue.
2) The "Geniuses" don't really have a clue about it unless the read these forums. Either that or they do a REALLY good job about playing dumb. They aren't bad guys; they have a job to do and rules to play by. Even if the rules suck, this isn't a good economy to wander off the reservation in.
3) There are still bad parts in parts supply chain. How do I know this: I took mine in to be repaired. I had the same conversation with the Apple tech on the phone. Logically, it made sense that getting a fixed computer would alleviate the risk of getting a new bad one. The result was an epic fail; the "fixed" panel was considerably worse than the old one. Yet, the techs at the local Apple store swore up and down that they all looked at it after the repair and that it was "perfect". I tried to show them the page here on this forum that exposes the problem; they told me they couldn't look at it because it wasn't Apple sanctioned. Whatever. Understand that this repair was done at a local Apple store; sending it back to corporate might yield entirely different results. Just be aware that it isn't guaranteed that you will get a clean iMac back.
4) Based on the above, I'm starting to think that there is a chance that some people literally can't see the yellow tint problem. Maybe it has something to do with store lighting; maybe it has something to do with color perception.
5) I wouldn't say that there is NO reason to buy a faulty computer: it depends on the fault, and Windows is a pretty good reason to avoid the alternatives entirely
I posted that I was going to return mine a few days ago, and I did, but I caved and ended up getting a new one (my old one was a refurb) and this one is significantly better. It is NOT perfect, but it's better than the first two attempts and I can live with it until Apple figures it out. I still feel confident that Apple WILL figure this out.
Like I said, I totally caved, and I feel almost dirty about it, but after toying around with Windows 7 for a day, I just couldn't bring myself to go down THAT road for any period of time. It's one thing to stand on principle, but not if it is going to make me utterly miserable. If Windows 7 had just been a little bit better, I may have done it.
Moral of the story: the yellow tint issue has yet to be completely sorted, and there is a chance that your repaired machine could wind up worse than the original.
Good luck with your decision; I totally understand/respect those that walk away, and I totally understand/respect those that hang in there. It just depends on your situation.