> Just for clarity, Open-Xchange has not written any xapian plugin whatsoever.

Yes but the doc says that Open Xchaneg "supports" one over the other.

 

Honestly, I am doing this over my free time, begin very reactive to user requests, and have this confirmed by Debian, Archlinux and now Fedora in their core packages

 

This is not very encouraging despite all the efforts achieved.