Derry-
I understand and agree with your post as to the age of GY tires now available to us. A five year old tire is uncomfortable to be mounting now as a "new" tire. I was able to find a rear set that were only a few years old, but I had to look hard to find them. But the Goodyear tire as Shadowman so eloquently states IS a good tire. Thanks, Bill.
Any tire/wheel combination can be optimized for a specific driving category. The FGT design team could not offer a singular purpose tire as the OE offering had to be "good" at every possible driving condition to which a GT driver might expose his (or her) car. High speed, high/low temperature, dry/wet surface at high/low temperature, snow, mud, ice, track events, noise, etc.,etc.
For owners to disregard with prejudice their OE Goodyears as lousy tires tires, speaks volumes as to the owners lack of basic understanding to what was involved in selecting the tires offered by Ford for our GT's.
Parenthetically, I do not work for, nor have any affiliation with, Goodyear.