My dining room furniture had some stain rubbed off from daily use of my 581 after only about a month, so I purchased the Ultra Soft Bumper, sold by http://www.robotaddons.com
. I've had no more damage since installing it. If you have curved legs, where the top of Roomba's bumper can hit first at certain points, get the double set. I've got the thin bumper on the top of Roomba's bumper, and the wider one at the bottom to protect my curved furniture legs. These bumpers also protect your moldings too.
I also put one of these Ultra Soft bumpers on my mother's Roomba, and she has had no damage whatsoever.
Here's a link to a review I did:viewtopic.php?f=10&t=12702