At a certain point, if your size/weight constraints are really that small, you've got to be realistic about what your micro-kit is actually going to be able to do for you.
I'm always baffled by all the tiny items in the smaller kits that don't seem that useful. It's like they're trying to make the contents list as long as possible. Safety pins, wire, a couple of very small Band-aids? So imagine yourself in a real survival situation. You got lost on a short day hike that was supposed to be a couple of hours, or maybe a back country mechanical breakdown or plane crash. What do you need
right now?
If it's getting cold and/or raining, I need extra insulation and rain gear immediately. If it's getting dark, I need a flashlight with batteries that will last several hours. I need a GPS so I know the way to the main road, so I don't walk in circles or in the wrong direction like James Kim (
http://en.wikipedia.org/wiki/James_Kim). It doesn't do any good to walk in a straight line if it's taking you deeper into the woods. If it's several hours or days to town, I need a water carrier plus some way of treating it. I won't really need food any time soon.
If I'm too injured to walk out (broken leg etc.), I don't think I will use a machete to build a shelter or a fire. I need a warm sleeping bag and the simplest possible instant shelter to crawl into. That's all I am able to do. Maybe a signal device like a PLB or a mirror or just a cell phone, if I have to sit and wait for rescue. If I'm injured, it would be helpful if my shelter and/or rain gear were blaze orange.
I'm not going to build rabbit snares. Not going to fish. Two Tylenols are not going to help me. I don't need a tiny razor knife or duct tape or a sewing needle to survive. Somewhere I saw a kit with one small piece of hard candy.

Yes, I can think of a possible
use for all those miscellaneous items, but they're not what I really
need.
I can just picture myself shivering and wet, sun going down, no idea which way back to town, with half a dozen safety pins and a stick of gum. Oops.