Here's what (I think) you need to change to use Fetish and still get the benefits from GU37.
Delete the following files:
*eq2ui_inventory_merchant.xml (see
here for the compare)
*eq2ui_mainhud_zonereuse.xml
If you want the "view intro" button that badly, delete eq2ui_newcharscene2.xml
Otherwise, most other changes are localization codes, or them changing tags to self-terminate. (" < tag args='arg' /> " instead of " < tag args='arg' >< /tag>" ).