Ilford were quite emphatic (on factory tours) that PET films can damage conventional camera wind mechanisms, and why they'd never use it again for 35mm. The films coated on PET are usually used in specialist cameras with slip clutches or other safety mechanisms that prevent damage in case of a film jam.
Originally Posted by clayne
For this reason the major manufacturers don't normally use PET base for films made for conventional camera use.
The issue is more of stripped gears in wind mechanisms because the film doesn't break or the perforations tear. Some cameras are far more robust than others but many of the low to medium priced cameras made in the last few years don't have the build quality of similar cameras made in 70's & 80's.
Ilford's comments were because there has been damage to cameras, so it wasn't scare mongering, it lead to their rapid withdrawal of their 72ex 35mm film, so they know what they were talking about.