Thinking of buying an iPad just for this use case. Most of my technical books are in PDF form, converting them to any other format ruins the readability, and the PDF on the kindle is terrible to navigate.
I would still be worried about battery life (as it requires much more effort to keep an eye on than on an e-ink reader).
And do not forget about the screen differences. It's still more pleasant to look at an e-ink than on the traditional display.