I would, yes. Especially over the vanilla Kindle. At least the Kindle DX would support full-size PDF's without panning. But I still think the delay in page-turn times on e-ink would give iPad the edge.
I was trying to decide between a Kindle DX and an iPad for reading PDFs. Ended up going with Kindle, and I'm loving it so far. The page turn delay has been much criticized, but it's actually faster than the older eink readers, even with the bigger screen.
And the text looks beautiful. No comparison to LCD is even possible. When I got my Kindle, I thought there was a piece of paper stuck to the screen telling me to go plug it in. That was actually an image on the screen.
But I'll concede that an iPad would have more functionality.
