Ive got a few bulk rolls of 100ft Pan-X squirreled away, and a number of bulk loaded rolls loaded up ready to go. Still a great film even though its way expired after all these years (no perceivable fog). I have shot a fair amount of tmax 100 and I dont think it matches up as a substitute. I think tmax 100 is a great film, its one of my favorites in 120 with its amazingly clear base, and acros is good too, but panatomic X just handles and feels different. Its hard to put a finger on it. Plus you dont need to always shoot landscapes with it, shooting wide in full sun is always a neat trick too.