At SSR at the end of August, on our first night, they told us at Artist's Palette we could grab a dessert or other snack item instead of a drink. It was the same at the other quick service at the resort. We could choose from dessert, salad, fruit, bottled drinks, or any of the packaged snack items-- pretty much anything that was a snack credit.
We didn't not try in the parks. I did try to break a qs credit into snack credits at BOG lunch and was told that they don't allow it there. I had no problem breaking meal credits into snacks at SSR though. 3 snacks per meal credit.