I think you could easily modify your Gorp by replacing the Chex with something more slow release, like a whole-as-possible oat but low sugar granola (would not be too tough to make at home...most commerical granolas are sickeningly sweet).

However, you raise the point of liking Gorp because it is what you are used to when out hiking etc. It may be that your pleasant associations (Gorp = doing things I love) is making it tough to see alternatives. The beef jerky/nuts combo sounds great.

I am a huge fan of fitness bars, and there are lots out there to choose from, depending on what you find you want/need in them. Check the labels and see what serves your goals. There is a nice new one available in Canada at least called Perfect 10...a bit high carb but that may suit your activity level.