Ooo, the Forma looks gorgeous, and 300dpi, too. For some reason I hadn't even considered operating the device in landscape mode, but that would be near ideal for much of my use. Good on them for depicting it in their product photos. An 8-inch screen is probably doable, then.
I should clarify -- most of the PDFs I intend to read are electronic component datasheets and scientific papers. They're exclusively formatted for A4 or Letter size pages, and I don't think I've ever seen one that was in color. I take it the PDF format has another traditional use around here?
Unfortunately, it sounds like
Kobo had ZIM support but broke it recently, so that's out of the running. (And I just confirmed with Kobo support that ZIM is indeed not a supported format at present.)
Dang. That's sort of an essential feature for me. And it looks like basically nobody supports it out-of-the-box.