Those are nice pulleys and one of the few with lateral-float needed for Shimano derailleurs.

The only failures I've seen with pulleys is failure to tighten the cage bolts properly. Wouldn't hurt to use a little threadlocker as well. I was in a slight downhill 45mph finishing-line sprint behind a guy who started weaving badly. I was around him before he hit the ground and I could hear all sorts of screaming, crashing and metal-scraping sounds. Turned out his RD cage has come apart and his chain wrapped around the rear-cluster and chainstay, locking up his rear-wheel. He had just installed aftermarket pulleys a couple days before the race, but didn't use a torque-wrench to verify the tightness of the bolts. Shame really as he worked in a shop and was in contention for the finish.