TMAX100 is on a par with Panatomic-X. Recommend TMAX100 anytime, you do not need to pine for Panatomic-X if it’s hard to come by. But if you can get some Panatomic-X by all means try it. You will get good results. You don’t have to make a project out of it or put it on a pedestal. It will just be nice. Yellow filter is a good idea.
TMY2 has more grain than TMAX100. Just a fact. It’s good though.
I’ve never regretted taking 35mm Panatomic-X or 35mm TMAX100 to the mountains. Nor will I ever regret taking 4x5 TMY2 to the mountains.
But I really feel bad about some shots I took on 3200 speed film because I got good shots that could have been more to my liking with fine grain. They make very nice postcards though, I think I sold a dozen.
Similarly, I regret using Tri-X one day from Dusy basin to LeConte canyon (because I had loaded it the afternoon before and had to finish it off). We had a dusting of snow with little rocks peeking through, just very appealing, but I felt Tri-X didn’t do it justice.