@glospete - Obviously, I'm not as paranoid as you, but
I recently had a puncture. Having attended to that temporarily, I drove around, until I found a tyre place that had
Plastic lower jaws on the machine (instead of metal)
Plastic upper roller on the machine (instead of metal)
Spoke to the supervisor, showed him my alloy which was unmarked before the work
Asked them to please take care on the machine
Inspected the allow after they had finished
The time the alloy is at most risk is:
Breaking the bead when the tyre is vertical on the machine
Damage to the rim from the roller, plastic/composite roller is better than metal (horizontal)
Damage from the hand tool used to ease the bead off the rim (horizontal)
If your alloy has spokes that are proud from the rim - this is when its most risky. The carelessness of the fitter can easily mark the spokes with the hand tool
And the place that I found with plastic jaws and plastic rollers? Kwik-Fit
Yes, there are horror stories about K-F - but it's all down to the skill and attention of the fitter.
So no, I'm not as paranoid as you, and there's nothing to worry about