When that article came out, I bought the ingredients and mixed my own, using instant green tea for flavoring.
A couple years later, I bought a case of "Powerbar Endurance" which is based on the same recipe, when REI had a 1/2 price sale on it. I still have half the case left. I only use it on rides well over 2 hours. I have done up to 130 miles with 9800' climbing using only this mix.