Okay, a few people have asked me to to this test, since I have some experience with Tmax 400 special orders. I purchased 5x7 TMY in July of 2001. Expiration date on box was July 2003. I had in freezer until sometime in 2004. It has been stored at room temperature since then. An unexposed sheet developed in pyrocat HD 1:1:50 for 10 minutes at 68 degrees gave the following base + fog numbers:
Visual 0.11
Blue (Ortho) 0.15
UV 0.35
I chose a staining developer because it represents sort of a worst case for us alt-process workers. As it gets older, it should be no problem to switch to using a non-staining developer for the remainder of its life.
This should give people a feel for how well this stuff will keep. It keeps pretty well apparently! So order up! I'm guessing that it should be good for another few years given the data I just noted.
Other notes about TMY: I have noticed that it is particularly sensitive to x-ray screening at airports. I mark my boxes when they make a trip through the machine, and I NEVER take film through more than twice. I learned this the hard way. I took 2 round trips a few years back and had really high fog levels. This is no surprise given the film's tremendous reciprocity characteristics.