If PDF file is mainly text, Sony reader will work okay.
However, if you are planning to read PDFs with table or figures (e.g. academic journal), then converting PDF into LRF using PDFLRF will yield the best result AFAIK.
https://www.mobileread.com/forums/showthread.php?t=13135
For download, please refer to post #435
Also, PaperCrop is a really promising tool.
https://www.mobileread.com/forums/showthread.php?t=31677
http://jupiter.kaist.ac.kr/~taesoo/p...index_eng.html
It can split complex PDF documents into smaller picture files quite well.
For example, this is the only tool that I know that can split 2 column papers with big tables spanning across the page properly. It only splits PDF into smaller gif/jpg/png but it can be trivially converted into LRF using comic2lrf included in Calibre.