I had need today to convert a very complex document (a 20 page syndicated media questionnaire form with thousands of items in a wide variety of tables, multi-column lists and other difficult layouts) to a format that would allow me to extract text labels for use in statistical processing.
To do so, I tried two free online PDF to Word converters provided by major PDF conversion software vendors and using their software:
PDFtoWord.com is provided by Nitro.
PDFtoWordConverter.org is provided by Able2Extract
The original PDF file is 337 Kb and 20 pages long.
The Word document from Nitro is about 3 Mb and 36 pages long (some of them blank). The formatting was mostly good, except for a tendency to wrap some lines, or place the last column of a multi-column layout on an addititional page. Pagination was generally way off from the original.
The Word document from Able2Extract is about 1.4 Mb and 21 pages long. Formatting was generally much closer to the original and pagination was preserved, except for one inserted page that contained an attempt to reproduce a set of navigation arrows (which Nitro completely ignored).
Interestingly, both programs converted the thousands of checkboxes used in the questionnaire to somtehing else: a dagger for Able2Extract and an ellipsis (3 dots) for Nitro.
Assuming that these results are representative of the respective desktop versions of the software, I would have to say that Able2Extract is clearly superior to Nitro for converting complex documents.