Years ago when I had typist that was not skilled to use styles and spec chars, tagging language was extremely useful.
But, nowadays, I think it would be much better if you make text only text processor as separate app based on QXP that will deal only with para/char styles, spec chars and tables with table styles too. No pictures, no vectors, just simple text. And no need of compatibility with any other text processor. It would be enough if it accepts RTF files only.
Everyone who uses QXP, or types text that will be used strictly in QXP, will be much obliged to have such text processor. This way, there will be no compatibility issues and no headaches when it comes to entering text.
Typesetter - Graphic Designer - Photographer - DTP Trainer