We have a running Xwiki 9.9 instance and followed the guide at :
To get rid of the xwiki/bin/view parts.
It works as expected until you try to create a new wiki, because the flavors are then retrieved with /resources/uicomponents/flavor/?xpage=flavor/picker_flavors&namespace=wiki%3Asubwiki
Where resources was configured with Url Rewrite Filter to be served as static, where it shouldn't be.
Basically it means that with the Short Urls guide above fully applied, one would no be able to select a flavor when requesting a new wiki.
Additional notes from Thomas:
the flavor picker can probably be refactored to use the REST API now instead of a custom hack like it does now