Nothing is taboo. Some things just get you chewed out.
I don't carry, but if I did, I would choose the basic Kindle e-Reader. It's lighter than anything else, the battery lasts a month, and it's pretty durable.
If I wanted to take an iPad, I would bring a portable battery pack, lithium ion. That way, I can enjoy my iPad over 3-5 days. Any trip longer than that and I'd either re-evaluate what I'm using the iPad for or I would bring a solar charger. Some places, like the northeast, a solar charger isn't altogether practical.
At a certain point, some trips in the woods don't allow an iPad (No!!!) But, I think in the next 5 years, we'll see an advance in technology that'll allow more use.
There's a project going on right now that's going to turn body heat and finger pressure into power for ultra-efficient screens. I bet before the close of this decade, phones power themselves indefinitely. Mark my words.