Actually, in a survival situation, I believe fats and proteins to be far superior to any carb consumption of equal measure. They pack more energy per given weight, allow the metabolism to regulate easier, do not require as much metabolic conversion prior to cellular utilization, are absorptively self regulating, and more efficiently support aerobic activity, which is what you are more likely to experience in a chronic survival episode (as opposed to running for your life, where the carbs would be preferable).

Since the focus of this thread appears to be away from meat based snacks, it seems that the most appropriate food blend would favor a greater amount of nuts and legumes, with high protein content grains included, and sugars used really only as a flavoring, not as a substantial source of energy. Candy bars with a large amount of nut content (like Paydays, as previously cited) are decent. Another really great snack in this gendre are sesame snaps, which pack quite a wallup of calories balanced in fats, proteins and carbs for their relatively small size (I believe 300+ calories in 3 ounces). I've posted links to sources for these snack items in the past.

Complex carbs are a good fuel source for your body in a controlled environment, where restricted caloric assimilation and nutrient balance is of greater concern. When I am trying to stay warm and functional in a cold, relatively inhospitable environment, I am going to be looking for a much higher, more concentrated, more efficient, and longer lasting energy source than what is practical to pack in a complex carbohydrate form.

Complex carbohydrates would be almost as undesirable as packets of table sugar in my BOB.