Over the past 25 years, I've probably owned 15 sets of non-hub centric wheels that used centering rings to make the setup hub centric. I've never had an issue with either plastic or metal rings, vibrations, etc.
My 2015 Outback has high-end Method Rally MR502 wheels and AT tires. The wheels use centering rings. We've had those wheels for 3 years, 20K miles, and lots of off roading too. No issues what so ever.