My opinion has changed somewhat. Now I think it's this:
It's 3 layers. Side by side, it's the exact same thickness as a Climber.
Knife blade, combo tool, corkscrew,
metal saw/file, awl,
inline phillips, magnifier.
Pressurized ink pen, mini screwdriver, tweezers and toothpick, tiny straight pin.
This was not a build that I thought of on my own. I saw someone else posted it on another forum, and I liked it so much that I built my own copy of theirs. I posted about it in the SAK modding topic a while back and I think I even included a link to the post that I copied it from.
It's just a Scientist with a metal saw/file added, but if you take the time to really think about it, the toolset in this custom SAK has nearly everything that you might need in only 3 layers. It may not have everything you might
want, but needs and wants are two very different things.
Prime example: if you have to cut through a piece of wood or plastic, then you might want to use a wood saw, but a metal saw will also work to cut wood or plastic in a pinch. It doesn't work in reverse. Wood saws can't really cut metal, so if you can only choose one type of saw then it's better to have the metal one. It may not be exactly what you'd want to use to cut wood or plastic, but at least it's going to do the job if you need it to.
Another example: you might want to have scissors, but in most cases a knife will work too. Scissors are easier and better for certain tasks, but a knife can usually get you by.
Need to trim your fingernails? The metal file is pretty aggressive. It'll work. It's even got a nail cleaner on the end.
The one area that I think is really lacking in something like this is a sturdy pry tool. The combo tool is a bit thinner than I'd like for prying. In every other area I think this is the best and most versatile tool configuration for the least amount of thickness. If you're trying to min/max, then it's hard to imagine how you could do much better than this setup without creating new tools or making improvements to the existing ones.
My hat goes off to the guy who thought this one up and shared it.