Hi,
I realize I'm a bit late to the conversation here, but I am a high school student so I thought maybe I could give some input.
The eDGe is in my opinion the ultimate device for students. The problem with high school right now is that many of the textbooks aren't available online or in a pdf format (depending on the publisher your school uses). You'll have to check the store though and some other textbooks sites ( If you would like a list of sites feel free to message me). As for reading books, for example, for a literature class, the eDGe is great because I can annotate, make attachments, look up words, highlight, etc etc. The journal app is great for note taking, although at first it takes some getting used to with the different screen size and the lag ( I don't really notice the lag. I have found that re-calibrating the reader screen really help with the lag however and to hold the stylus as if I"m writing rather than poking the targets).
I fully recommend the eDGe, the main problem is my school wouldn't allow me to connect to the internet with my device, limiting some of my functionality. I would say the only way you will know how much use you would get out of your eDGe as a high school student is by talking to your teachers and technology staff about access you would have to the network and the availability of online books. Teachers would also need to be flexible about posting things on line rather than using all printed sources, which may be difficult it you are the only student with an eDGe and all the other students are still using pencil and paper. The eDGe is a great device for students, but it will be very difficult to use if your school isn't very supportive of allowing students to bring their own computers/ devices to school or are not very up to date with the integration of technology into the classroom.