I finally got an opportunity to do some driving with these mirror brackets. Brackets are awesome. Cheap ebay mirrors aren't quite as awesome.

The mirror glass shakes a bit inside the housing while driving. I can tell it is an issue with the mirrors rather than the brackets because it happens on smooth roads (from turbulence) in addition to when hitting bumps and rough spots. I can place my hand on the mirror housing while this is happening and feel absolutely no vibration.

It's not horrible, and for the $70+ I saved vs buying genuine OEM mirrors, I'm not upset. I'll probably get bored sometime and see if I can modify the mirror in some way to improve it.