Just to report back on my experience, I got a kindle 4 non-keyboard, non-touch, and have been happily reading a (cropped) PDF file in landscape mode. The file is a few hundred pages of A4, and has a single column of text on each page. It works just fine for that.
If I want to read PDF files that have multiple columns of text per page, I think I will crop those files so that each column is on its own page, and read in portrait mode (I haven't tried that yet; perhaps the device has limitations on page aspect ratio -- if that turns out to be the case, I guess I'll just limit that when cropping by chopping up the column into multiple pages).
So, you can ignore the conventional wisdom that e-ink ereaders are no good for reading PDF files, as long as:
- you want to read A4 format text with text that isn't too tiny relative to the page, rather than things like comics or single-column text formatted with PDF paper size larger than A4, or single-column A4 pages with very small font size, and
- you have a tool that works well for cropping (I used briss for this first PDF file -- that got the job done extremely quickly with little fuss), and
- your eyesight is fair (text size seems about perfect for me under the conditions described above)
Thanks everyone for your help.