and then there is price.
let's say you made your own carb-infuse milk sport drink: about 25 cents for 8 ounces of milk and another 25 cents for the banana. that would be total of 50 cents. (another way to infuse milk with carb would be to add 1.5 tablespoons of maple syrup)
a commercial sports drink would run you up to 10 times that amount.
at the other end of the 4:1 ratio spectrum are the non-dairy milks such as rice milk and almond milk. they are great on certain nutrients but low -1 or 2 grams -on protein
dairy might not work for your digestive. many Americans suffer from lactose intolerance,and other feel icky and bloated when they consume dairy. other are vegan.