Fat loading vs carb loading is not the issue here, nor is "optimal" (whatever choice of that term you mean) energy, or the low carb diet. All of these concepts assume that you are in a "normal" environment where water is readily available. Items like Datrix were designed for survival at sea. That requires some energy (potentially to keep warm or to maintain brain function) while essentially inactive. Water is assumed to be in short supply (since at sea it usually is). The amount of water required to DIGEST the carbs is significantly less than that required for fats or proteins. Even the type of carbs is an important choice for this use. It has nothing to do with how dry your mouth feels after you have eaten the food.

For most long term food storage problems, Datrix is not the best choice. For some short term problems like flying (where you might easily be stranded in a low water situation) or at sea, where you will certainly have a shortage of water the Datrix is far preferable. These survival foods are designed to use little water to digest, be easy on the gut, last for a long time in bad storage conditions (have you ever opened a lifeboat on a tropical cruise?), and with rough handling (like the seat pack of an ejection seat). They must also meet the needs of people with common food alergys (say peanuts) and religeous preferences. You may make your own selections there.

The Skippy or Datrix question cannot be answered without knowing what situation you are in. In my car in Florida (as Art pointed out) the Skippy is just great(although I prefer The Peanut Butter Company Bee's Knees). In my Cessna flying over Arizona (or even much of the great plains) I would be much better off with Datrix bars.

Respectfully,

Jerry