It wouldn't take TOO long to file the smallest driver down. However, you might wanna consider actually filing down the medium one. I always seem to either need a regular size flathead, or a tiny one, never a smallish one.
I just got a CS4, which comes with an awl. I intend to stick it in my range bag, and I understand the small driver is the perfect size for sight adjustment, which is why it would go unmodified on any Juice I get.
I also recommend filing down the edge of the can opener. It will open cans much better after you do. The side to file down is the one that is next to the scissors, this also means it slides against the scissors a little easier when closing.
Just my thoughts.