Adco-I know what you mean and what Thor means and its good to try them out as mileage is building so you dont' blow a major ride with the wrong food. For longer swims (where my digestion is more of a problem) I always had what usually works, a back up that generally works and then something completely different for the actual channel events. To that end I found adding the things I need into the drink helps more than premix-I use water, diluted juice or green tea as a base (and several other swimmers have found the last to be best) add in carbopro which is a type of maltodextrin, then electrolytes (bought the powders from now foods and add salt). For cycling my stomach is easier than swimming but I need more salt. (my blood tests show a perpetual low sodium and after a ride its sometimes a full deficiency).
So I mentioned the potatoes (more potassium than bananas) , these are boiled new potatoes in a size small enough to consume direct out of the pocket and I throw sea salt on them, I have electrolyte tabs for when its getting worse (I like the new saltstik chewables and the old caps) water and sometimes I add vitalyte if my stomach is acting up, it comes in single serving pouches so I can just dump it in as needed.
I also have enjoyed fig newtons (get the king sized 2 cookie packs), pb&j cut into bit sized squares, banana (but not before a hill). Most of this is old school stuff that you can make at home and carry in a pocket. I've made my own re-creation of the original powerbars (used to get those in the late 70's) powdered milk, peanut butter or almond butter, some salt and honey use enough powdered milk to form into balls and roll in a little cornstarch and again eat out of a bag in your pocket. I am interested in real foods we can keep in our pockets or belts and eat and higher electrolyte are a big plus!