As many here say, best reader device for PDF is the one that is sized A4. The ones with 6" display seem to small.
From what I have seen, PDFs can look good on 6" display, it all matters whether the device support reflow feature.
I for one, am really waiting to get my BeBook and don't hesitate to read my PDF files with it. There are some topics I have requested screenshots of my PDF files on BeBook device:
https://www.mobileread.com/forums/showthread.php?t=52950
https://www.mobileread.com/forums/showthread.php?t=53260
When I get my BeBook, I will write a review here on how it adapts to PDF with the latest firmware.