Race application = bad
your daily driven bolt-on car = perfectly fine
The only break down of a engine proven to be due to the pulley was a 7000+rpm 5.4l race motor, no one has proven or shown a 4.6l bolt-on car breaking. I've been reading this site since 2000 and not seen a single thread of a person saying: PULLEYS BROKE MY CAR!!! Only people claiming they would. I know many GT's and Cobras and Mach1's ever GT500's with them, NONE have had a failure.
Please explain the parameters that define what you consider "proof" in the scenario you are speaking of. I would like to know what differentiates that particular failure from all the other engine failures that have occured with small dampers.