I think it's been about 20 years since I've processed a roll of film so take anything I say with more than a grain of salt, but back in the day I was never happy with Kodak t-grain films. They just seemed to have a tonal signature I didn't like and couldn't overcome. It got to the point where I could even spot it in other peoples prints. This will sound crazy but they never gave me a sense of visual sharpness, in spite of their high resolution. AFAIK, T-Max developer has T-Max in the name but is not specific to or optimized for T-Max films. It's good for pushing. I never got comfortable with Xtol due to variability. Ultimately I settled on FP4+ and a couple Crowley developers, FX-2 and (I think) FX-37. Wasted too many hours and too much money on t-grain before I saw the light. Oddly, the photos in the first film catalog for Kodak T-Max films were fantastic.
Really? Because AFAIK there are no regional standards organisations anymore. They're all under the ISO umbrella and charge a standard, extortionate, rate equivalent to around 40 Swiss Francs for any standard that's in current use. Downloaded or paper version.
I did manage to find some old Indian Standards online, which were roughly equivalent to older ISOs, but the ISO police the Internet and take down anything that even remotely gives a clue to what's in their standards. You can't even find a dimensioned technical drawing of a stupid ISO hotshoe!
I can picture their stunted hominid forms, stooped over in semi-darkness and stroking their database, muttering "Precious, precious. Mustn't let anyone get their hands on the precious. Well, not unless they pay through the nose for it!“
The main issue with the 500mm/f5.6 PF is now that it has the wrong mount, for those of us who use a Z8, Z9 or Z6iii for wildlife photography. It is not a huge deal, but at least I would much rather not use an adapter.
The problem is that pretty much all used F-mount cameras and lenses have lost a lot of value. Nikon introduced the 500mm/f5.6 PF @ $3600 back in 2018, but used value now is around $1500. The price for the Z 600mm/f6.3 PF has dropped a couple of times from the initial $4800 to $4300 to now $4000, but that means the cost for switching is around $2500 for a mostly lateral move; that is a pretty steep price to pay. If used value for the old 500mm PF were between $2000 to $2500, it would have been a much easier change. (I try not to say it is an upgrade, because it is a pretty small upgrade.)