"Pretty much everyone has found it (Polypan F) to be quite different to Pan-F, not least in terms of hardening, and a range of other aspects including grain size."
No, not me: besides a slightly longer dev time needed for the same contrast and the missing halo protection of the clear light blueish PET base
I can't distinguish one from the other. I made a side by side comparison developed at the same time in the same tank:
https://flic.kr/p/oLxffw vs
https://flic.kr/p/oLxzKk look for the biggest file
"OR the manufacturer is unwilling to admit that its film is being repurposed."
That`s exactly my estimation and would fit to the recent Harman philosophy.
Polypan F was distrbuted in Germany by lumiere (lumiere-shop.de).Most cans (if not all) of 90 and 152 metres were sold by them for some years. They didn't sell any other sizes nor 135 canisters, Maybe he bought the whole batch from the manufacturer. I bought a 90 m can and one of the very last 152 m cans (expiring date 12/2015) on a photo market, where I could talk with the luniere-owner. Of course I asked him who made this film and he said that it's a cine copy film made by Ilford. But one batch would have been unusable for the original purpose (missing border printing?). It would also explain the 90 and 152 m sizes only, all 135 canister packaging may have been made from these by others.
But it's of cours an academical discussion. Polypan F is not available anymore at reasonable prices. Should I auction the untouched 152 m can at Southeby's and by a car from the avails? 4-digit offers (€ or $) via pm welcome