Swap the razor for a SAK or multitool. If you take the SAK, a small pair of needle nose pliers is a great thing to add, particularly if they have GOOD wire cutters. You can find barbed wire in the darndest places.

Bigger water bottle, maybe even a pair. I really have come to like having a Gouyet stainless steel bottle in my gear, just as much as I like have a GSI/Olicamp cup on the bottom of my lexan bottle(s).

+1 on the dental floss. It's tiny and darn useful.

I know people like their Fenix's, but a headlamp is so freaking useful. A year ago, I would have said "well, their OK", then I got a good one. It's been in my EDC since the new year. :P

And the reason some people don't suggest pre-shaving the magnesium is that it will oxidize. IIRC, the oxidization reaction is largely self limiting, so it is only the surface, but a spark or even a match won't light it at that point.