Anyone have one of these? Yay or Nay?

We just got a new kitchen table, chairs, and bar stools for the island, where my 3.5 and 5.5 year old eat many of their meals. The stools are backless, so they no longer support the Graco Blossom boosters we used to use. The 5.5 year old is fine without a booster, but we're finding that the 3.5 year old just doesn't fit well in the generously sized stools/chairs, and it's causing her to be up and out of her seat at meals. I don't really want to put the Graco on our new chairs, either - I feel like it will scratch the seat/back, and will look ugly.

Does anyone have the OXO Tot Perch boosters? The one without the belt? I'm wondering how well they stay put on a chair seat (no sliding around), if you've had any issues with the booster scratching your furniture, and how easy it is to clean. Thanks!!