First one needs to consider expected terrain and weather.
Then why and what are you E&E'ing from or for.
How many are you responsible for and what training does everyone have.
What "comfort level" are they going to be needing.
I think one could do well by adding the AMK/DR PSP and an AMK Heatsheets or Bivy. as a start. I would also consider adding this military survival kit if space and finances allow. I have used all of these items and REALLY USED the military kit once in 1989. A water bottle might be nice also. Helps to have something other than the bag in the military kit to purify/drink from.

Just a start. I am helping two families establish themselves in the BOB world. They are light years apart in thinking, finances and "comfort level" so their bags differ accordingly.
Good Luck