My old Sony T 1 has PDF text reflow pinch zoom in/out making it is much better than my old Kobo wifi reader. Then my Kobo touch improved their PDF firmware making it better but not as good as the T1.
Text reflow helps but sometimes it doesn't work depending on how PDF is formatted. Best to have large screen that can display full page large enough to be easily read. Some PDF books and documents really need large color screen.
Sony 13.3 inch DPT S1 review
http://blog.the-ebook-reader.com/201...-paper-dpt-s1/
Mobileread Sony Reader Forum
https://www.mobileread.com/forums/forumdisplay.php?f=10
Mobileread Onyx Book Forum, Onyx Book has some larger screen readers and is working on 13 inch screen reader. Reading this forum some models might be a little buggy.
https://www.mobileread.com/forums/forumdisplay.php?f=220