Good old "Adventure Alan" published his own list of "13 essentials" that he describes as an "update for the modern hiker".
He lumps map and compass as "navigational tools". In my case I never carry a compass and am unlikely to start. Where I go, topography along with the ability to read a map does just fine. If I was in the bush in Canada where you never get long views and everything looks much the same, a compass would make sense, but a GPS would be even better. Note though that a map and compass never need batteries. I have never carried a traditional GPS unit and am unlikely to start. The maps suck. My cell phone in airplane mode goes a week, has a fantastic GPS, and carries the 7.5 minute topo maps for the 6 states I hike in.
I don't really think a trip plan and staying found belong on the list. Both are entirely valid, but the "essentials" are supposed to be tangible objects to stuff in your pack.
I am unsure about the SOS device. On one hand it makes sense for the intelligent experienced hiker, especially the one who goes solo into remote areas. The ugly issue though is the epidemic of nitwits who carry and abuse them (I have had long talks with backcountry rangers). This abuse doesn't negate the sense of a person carrying one who will make the right choice of when to use it, so I agree here, having used this opportunity to grind an axe.
Water is always a good idea, the most vital thing here though is between your ears -- knowing your requirements relative to the weather and the area you are hiking in. Nutrition makes sense as far as being well fueled in order to do whatever it is your orignal plan entails. As far as something to carry for an emergency -- I think this is bad logic. Anyone can go a day or two without food if needed and carrying a pound or two of extra food on every trip "just in case" is something I cannot justify.
Tom's backpacking pages / tom@mmto.org