I put bar end mirrors on my 821, not so much due to vibration but to see more than just my elbows.
After settling on Rizoma, I went back and forth between the Spy or Retro. In the end, I went with the Retros. I really like the look of the bar end mirrors and it did take a little while to train my eyes where to look.
The only thing that surprised me about the Retros was how small they actually are. It was difficult to tell in photos. That being said, they still work great and even though they are relatively small compared to OEM, visibility is very good.
Paul