seals for 10 years and 30,000 miles.
No problems
Questions to PYI have been answered competently and rapidly.
We replaced the rubber bellows after 9 years. No visible deterioration, but PYI recommends this.

The issue of the collar sliding forward is obviously potentially serious. We just tighten the set screws and are happy with that.
Jon Eisberg idea makes sense. Could also perhaps do same with at hose clamp on the shaft.