When touring in the Czech Republic, I always had .5L of beer with lunch. After lunch, I was a bit weak for the first half hour, but then felt fine. Good carbs, good hydration, fine taste, cheaper than water. I don't do that here, though. Water's free, the beer's usually not very good, and I don't need the weak 1/2 hour. We ride our tandem out of the BR most Sundays.