I thought about using a smartphone (or other smart device) to run a custom pipboy flash app. My flash coding is now extremely rusty and I only took one class on it. I'm sure a flash app would kill battery life though, especially with the mp3 streaming :/
I get pretty good bat time with my Pharos, but nothing like I would like. My first Pipboy is just going to have the tomtom one, and the bat in that lasts quite a while. Not sure how long, I've never measured. I may replace the start up screen "please wait" with the pipboy screen. But there wont be much function other than the GPS with it. I will add a few dummy lights and stuff to greeblie it out though.
Once I finish that one, I will place the Phaors in the second one. Tweak the functions and stuff. Plus I may be tearing it apart to fit it in, so I may be able to replace the battery with a bigger, longer lasting one as well.
I purchased the extended GPS antenna, which I want to build the glove part of the Pipboy that is usually over looked, and place the antenna on the backhand of the glove, running the cable up to the pipboy. I think it will look good when I'm done.