Compared to other brands I've tried, I love how the Z60's side brush extends to reach every edge. It really does try to clean as much as it can and stay as far away from cables as it can, which is so cool. However, because some of my furniture is hollow, the brush tapping against it creates a loud drumming noise. This isn't a design flaw, more like a flaw in my furniture lol & quirk of my house.
To fix it, I taped a tiny piece of soft velcro to the side brush. Now it's perfectly quiet and still cleans flawlessly without scratching (it never scratched to begin with, my previous old robot did though). Just a quick DIY customization!