I was hoping to use it primarily for flavor, but if it's fermentable, I guess it'd do that, too. I'm not familiar with diastatic powder—what's the deal there?
Here's some reading on the "third beer" concept: http://web-japan.org/trends/science/sci050715.html
The "third beer" boom was sparked by Sapporo, which launched a beverage called Draft One in February 2004. Made with protein extracted from peas, Draft One's selling point is its light taste and drinkability. Meanwhile, Kirin's Nodogoshi Nama, made with soybean protein, touts its good flavor and crispness. Asahi's Shin Nama, which uses soy peptide and a yeast that the company also employs in beer making, offers a dry finish. And Suntory's Super Blue, which contains low-malt beer mixed with liquor distilled from wheat, has a crisp, refreshing taste.