I'm only shooting colour negative for the foreseeable future, so time to move this on.
Purchased 450 sheets from a local artist / photography teacher who was liquidating his darkroom. I was told it has been continuously frozen since purchased new (it was even in brought to me in a cooler). I've since kept it frozen also.
I've been shooting a few sheets here and there from two 25 sheet boxes purchased in the same lot. See below for a very unscientific (and uninspired) comparison test I made with TMX (Xtol 1+1, scanned in sleeves under glass on an Epson flatbed).
Fresh TMX Left - Ektapan right (expired 08/1999, processed 2024).