I have used this in a simple sweet-sour kvass at about 2.5% of malt. This was an all malt kvass (non-traditional in not including bread or flour, or beets or fruit for the fermentation, but traditional in execution, using a natural sourdough fermentation). My intent was to give a little toasty sweetness to replace the missing breadcrust flavors and aromas, and I think it worked well. I wasn't looking for a lot, just a note to harmonize with the fruity sweet-sour base and it worked really well.
I used this once or twice in brews and to be honest I need to try it again. I am leery of it after throwing half-a-handful of dry grain in my mouth to taste. This stuff is nasty. I think I am just going to make a hot brew with this grain to see what the tea taste like.