Kudos to WF for coming up with something 2 years out of warranty

Brickbats to the contractor for hanging their hat on being 2 days past their warranty. I can't imagine doing a customer that way.

Stick with WF but lose the present contractor if at all possible.

"However, I would venture to guess that units with 5 year warranties vs. units with “standard” 10 year warranties are built from the same parts."

True, and parts break. Warranties are an insurance policy. Like any other kind of insurance the more coverage you want, the more you pay/ the higher the underwriters exposure, the more they charge.
I continue to be astounded by the number of people who think warranties should be free and flexible.

We have covered the comparison of a geo system to a car before. It is not a good one.
Suffice it to say, at the top of this forum when we say dealer is the number 1 thing that will impact your geo experience, we weren't kidding.

CBox,
I have a suspicion that your second/third opinions may not agree with original contractor. While I don't agree with you that this stuff should automatically be covered, I would much prefer that your installers behaved more accomodatingly. If you find their diagnosis is wrong, I would use that to lever a discount on their end.
I also suspect your electric bill may hold evidence that your trouble ocurred before warranty expiration.
j

No one feels happy when something fails just outside the warranty period, but that is just part of life. I had a crankshaft fail in a Lincoln Towncar at 47K miles, which I think was within warranty on mileage, but because it was outside of warranty due to time, it wasn't covered. I come from an era when Lincoln was considered a mark of excellence, so you just don't expect a total engine failure like that, particularly when the vehicle seemed showroom new.

But, them's the breaks.

Used to be that a warranty was determined more by guess and by golly, but these days a savvy consumer needs to regard it as more indicative of product lifetime. Recently, I have seen an increasing number of what appear to be engineered life-limiting component failures. If you are purchasing a major product, you need to either put your faith in a reputable "professional" with the term denoting a person who can be expected to put your needs as a customer ahead of more immediate personal gratification, or you need to do your own research into what you can reasonably expect from a product. And, even then, you can be surprised. The warranty only helps prevent your surprise from becoming economic disaster.