I initially picked up the board with just the roller...based on the reviews the cushion was too easy and people quickly switched to the roller. I on the other hand had the roller and quickly went and ordered the cushion.
I'm glad I did, it's more stable and I can actually balance (a little) on it. So far, I've only used it in five minute increments...but it's a start and at least I'm using my purchase.
I'll update my progress on this.