Has anyone tried a meditation bench like this?

http://www.catizone.com/meditationbench.php

It has rounded feet, which means that it's inherently unstable. I can't sit on a cushion easily, and I've tried other benches in the past which don't "rock" like this one, and I'm wondering if this is easier or harder to sit with because of its dynamic nature.

No, there's no way I can try it out before buying...