Interesting idea to hide features and activate it only for customers who request it. similar to gmail labs in my opinion.
In our case, it slowly became difficult for us to manage the interface with many permutations possible based on what features were active. For now, we put that hold. Did you get into any such issues?
Haven't tried antiword. As of now I find abiword pretty stable for both doc and docx. I need more data but I found a few cases where it just hanged while converting. There is no specific pattern to when the program hangs. For now I am logging such cases and timing out the conversion in 3 seconds.
Tika is very good at converting documents to plain text. Very reliable too. The problem for us was that, most resumes have a lot of formatting in them. For example candidates use tables to structure data. When such a resume is converted to plain text using tika, it looks jumbled.
Will take a look at pandoc. Thanks for suggesting.