I don't think I could do all the editing I need to do in calibre. The conversion of stories in PDF format to .docx by Adobe.com kinda mangles them - it insets section break scattered through the document, sticks extraneous paragraph marks in the middle of some paragraphs and puts multiple spaces between some words (just to name a few things). I've worked out a multistep procedure to clean them up. Calibre converts the .docx to .azw3 and they display properly on the Paperwhite (TOC and all).