Hello Ian,
With a growing number of alternative 35mm films now being marketed on Polyester film base just how safe are they for conventional still camera use.
From my own experience and the experience of other professional photographers: They are extremely safe. We've never had any problem. Not with Kodak Technical Pan (ESTAR base = Polyester), nor Agfa or Fotokemika/Efke, Maco, Rollei, Adox films.
Used in different older and in modern motor cameras with 8 fps.
The modern PET films are safe, because they are designed for use in motorised cameras. Most of surveillence and aerial cameras have powerful motor winding,as well as modern 35mm still cameras.
And the modern (last 25 years) cameras with built in motors have sensors. If there are any slight problems (resistance) they stop the motor to prevent damage.
Do a search here on apug or on photo.net.Try to find someone reporting that his camera was damaged by polyester film. I doubt you will find anyone. I have never heard that this has happened.
On last years Ilford factory tour the Chairman, Howard Hopwood made it clear that under no circumstances would the company supply 35mm camera film on a Polyester base again. He pointed out that prior to his joining the company Ilford had been making & selling special 72ex 35mm film on a thin polyester base, while he didn't say the full extent of the problem the films was withdrawn, some cameras were damaged.
They don't tell you the whole story: I've used this film, some colleagues as well. The problem with this film was not the polyester base. It was that the base was simply too thin. The modern PET films are much thicker, similar dimension compared to triazetate.
Ilford made the base so thin to get the long 72 exp. roll into the cartridge.
The problem was keeping the film flat in the camera. It had too much room to curl slightly in the film channel. Because it was too thin and not stable enough.That caused sometimes some transportation problems. The motor then stopped. But the transportation mechanism was not damaged.
If they had used a thin triazetate base for 72 exp., it had caused the same problems.Probably much more, because the thin triazetate base were torn,not stable enough at that "thickness".
Because of the very thin base, loading it on the Kinderman or Nikkor 72 exp. reel was like trying to wind up wet toilet paper

Not only was the base too thin - the emulsion was different to normal HP and it was difficult to get decent negs from it.
All in all, in this case Ilford did not a good job with this film. But it had nothing to do with the polyester base.
He also pointed out that no major manufacturer used polyester film base for 35mm film.
That is wrong. Agfa-Gevaert is making it,and they are producing much more BW film p.a. than Ilford. And Fotokemika / Efke (in consequence Adox CHS,too) has recently changed the film base from triazetate to polyester. The latest batches are already coated on PET.
And Adox CMS is coated on PET, too. Never had a problem with this film (at least concerning the base).
Acetate film will tear if there's a film transport problem, usually at the sprocket holes, but Polyester is too strong and damage can occur to the transport/wind mechanism, potentially worse with a high speed motor drive.
No, the modern high speed motor drives stop winding immediately if too much resistance occurs. No danger of damaging.
Are the manufacturers selling us film on Polyester base irresposnsible ?
Ian
No, they are not. Not Kodak, not Agfa-Gevaert, not Fotokemika, not Adox, not Rollei-Film, not Fuji.
Regards, Michael