Welcome to MobileRead, sharp21!
I'm glad you're doing your research first so you won't get something and be disappointed by it.
The iLiad is the best e-ink device out there, at the moment, for A4/Letter PDFs. Though it only really manages it by virtue of turning the pages sideways and panning/zooming.
There are a number of utilities to slice-n-dice them so that they're more or less readable on a 6" e-ink device, but there is presently no e-ink device that handles A4 PDF files flawlessly.
If you're willing to step out of the e-ink arena, then you have the option of Tablet PCs, but that would also require that you accept an M$ OS of some stripe, which is not acceptable to a lot of folks, particularly MacUsers.
Unfortunately, that about exhausts the options. There are predictions of e-ink devices with large enough displays for A4 PDFs, but they're a few years off yet, and they're just predictions so far.