I take my iPad on all my overnight tours. Battery life is great, plus I have an external battery for multi-day trips. The tablet is light, the battery isn't too bad either, but I did find that between a phone, backup battery, camera, tablet, iPod, and associated cables I had dedicated a significant amount of space to electronics. Still worth it, though.
But I don't know if a tablet is an answer to your problem. How much storage do you need? I have no problem loading my photos into my tablet, but I also do not capture RAW images, so I don't know the space requirements. I don't know about HP, but with my tablet, moving the photos was a one-way trip until I got to a real computer, meaning that if my tablet didn't have enough storage, there would be no way to move those photos to an external drive while on the road. HP may not take Apple's my-way-or-the-highway approach to data management, so maybe the tablet + enclosure would work for you.
If the tablet is in your budget and you have more use for it then just storage, I love mine. But $200 just to drop a pound of gear wouldn't be worth it to me if that's the primary goal. I'm assuming you actually want some kind of computer with you for information, maps, communication, etc., but if not maybe you can just load up on storage cards. Depending on how many you need, that may not be cost effective, but the weight savings would be substantial compared to any computer you'd carry.