Wobble board; floor or carpet??

On the forum, discussion came up about working with the wobble board on the carpet versus a harder surface (non-slip of course). Here is an example of 1Kid doing the wobble board on either surface. He's been doing them on the carpet, with a lot more ease. His specialist noted that he SHOULD be doing them on the harder surface, hence the greater challenge, much to 1Kid's chagrin. Pardon the camera hogs (2Dogs).