Yea, I probably could have been a little more diligent about finding a company who does more thorough testing. Every time I complained, we attributed poor performance to flex duct temperature losses. Summer of 2010, the owner of the company responded: "I really dont see any issues with your system and spoke in-depth with my technician and he said it was on the money."
Of course, the thing that was on the money was the subcooling and superheat values. This seems to be a good example of - don't rely on just those values to determine if everything is working ok.
I finally started taking a better readings at the appropriate locations before and after the evaporator, started doing BTU calculations, and was able to prove that something wasn't right. Funny thing, this company still hasn't taken their own detailed return/supply temperature measurements - they are taking my numbers and passing it on to Carrier.
And I can't blame just this company, I did call someone else to get another opinion (last summer I believe). This was the guy that punched a hole in the return flex duct, took a quick measurement, compared to supply temp at nearest register and said everything was fine. I realized at this point, that this larger, Carrier dealer was not going to be able to help either.
Will post another update when I have one.