Jim and I hiked the HRP last year and posted a pretty thorough trip report that offers one opinion about many of the things that have come up on this thread. In case any of you haven't seen those two posts:
Part 1 HRP Trip Report
Part 2 HRP Trip Report
And about MAPS... Alan Dixon and I have researched using the iPhone/iTouch/iPad as a GPS/map device. There are a few things you all should know. It can be a GREAT solution for the HRP, and I wish I'd had it. (We just used an iPhone for a six week hike in Turkey, so we've had field experience). In advance of publication of the article, here are some tips...
1. Three two apps you should look at: Gaia GPS - Offline Topo Maps; and iPhiGeNie Maps of France. Each of those three apps offer different things, so you probably want to use all three (they are dang cheap). All of them allow you to pre-download all the maps, so you don't need a WIFI or cell connection while on the trail. Gaia gives you OpenCycleMaps, Galileo gives you satellite images (more complicated and less important than the other two apps), and iPhiGeNie gives you government published IGN maps. Fantastic stuff - honestly.
2. Read the "Battery Life" section of my earlier post. I found a few more things that are covered in the not-yet-published article, but this will get you started.
Send me a PM if you have questions about the iThings maps and apps, or about the HRP.