I don't think the OP is specifically looking for users of the product, but rather information on whether such a product (which many users probably have never heard of) would actually be useful to them. I sense that sales have been slower than anticipated and this marketing person is trying to figure out why.
I never even heard of Page Zephyr until just now and I went to their website to find out more.
It appears that it just extracts content (really just text only) from InDesign, QuarkXpress or MS Publisher files and has an interface to upload the text to Google Docs, Scribt, Wordpress, etc.
While they are tageting several different markets, it appears they are more focused on Coporate and Legal markets as a way to plow through mountains of documents for legal discovery, corporate communications, etc. and quickly upload text to the web.
All very well and good, but in the corporate and legal spheres, most of the content inserted in page layout programs has originated from MS Word or other word processing programs.
And Page Zephyr doesn't search Word documents!
I'll bet that in these industries that the vast majority of archived documents are MS Word, etc and not InDesign, Quark, MS Publisher documents.
And these page layout documents probably just duplicate the info that is already available in the Word docs.
The other markets are Graphics professionals and News/Advertising/Publishing and allows for quick searching of specific info in IND, QXP etc docs.
This could be useful at times (I'm sure at times we've all had to open many different documents to search for something) but, and this is only my opinion, I think that the majority of people who come to these forums are more concerned with converting document (Q2ID, etc.) rather that grabbing bits & pieces of content here and there.
While the need to repurpose content will only get bigger in the future; and thanks for trying to create the tools for this. why just stop at page layour documents, why not search all MS Office docs too?
And while you are at it, allow people to harvest more than just text; when repurposing content, photos, graphs, charts, etc. can be equally important.