A brief note in response to your concern:
One of the XSLTs for DOM authorities is moved so it can be used by both biblios and authorities... we'd need to confirm that DOM authority indexing still behaves itself on both upgraded and new installations. Other than that, we're pretty safe to include these files, even if they're still being tested and developed (and what part of Koha isn't?) Users can make the choice to opt-in, or leave things as the default and experience no change.
The XSLT in question, koha-indexdefs-to-zebra.xsl is not actually used by Zebra in the day-to-day business of indexing. It's used by developers who are revising their DOM index definitions themselves. As far as I know, Galen and I are the only two people who have modified the authorities DOM configuration, and therefore the only two people who have actually used that conversion script, most likely. As an aside, Galen and I briefly discussed the wisdom of storing the generated authority-zebra-indexdefs.xsl in the git repository, but concluded that there was no reason to add a dependency on xsltproc, given that the file rarely needs to be regenerated.
In conjunction with the Solr work that BibLibre and others are undertaking, I'd like to toss another idea out -- of starting the process of deprecating GRS-1 use in 3.10.
Regards,
Jared
--
Jared Camins-Esakov
Bibliographer, C & P Bibliography Services, LLC
(phone) +1 (917) 727-3445