Very interessant.

But why, then, does my "expired in 2005 but shot in March and developed in April" Pan-F look like your "Expiration date 2015, exposed & Developed March 2012"?

If the "poor latent image" theory was true my negs should show no markings at all. But yet they do and they are very contrasty. This clearly contradicts the theory. And yet, I've also had very faint images shot on fresh pan-f.