I have not personally seen any…
It would be hard to find conclusive evidence of increased bearing failure at x rate faster than stock unless a test were done on two or more idential motors in a controlled environment with stock and undamped pulleys. There are too many factors in real world driving to be able to pinpoint a specific increased failure rate.
Again, these results would be unique to each model of engine tested, so I would search around on whatever forums are specific to your car. I researched b-series motors, and I found no evidence to convince me not to run one, and plenty of people who have been running them for a quite a long time with no ill effects. Maybe a hyundai v6 will explode in a week without a dampened pulley, but I have no idea.
Their only real benefit is how fast the engine will change rpms, just like a lightened flywheel, which you will find beneficial if you heel-toe downshift/revmatch. If you are looking for the 1hp it will gain you but dont care about how fast your engine changes speed, save your money for real power building mods.