Can I upgrade the Subversion server installed by TeamForge to version 1.7.x?

Not for TeamForge 5.4 and 6.1; with TeamForge 6.1.1, this is possible.

Subversion is provided as part of your TeamForge installation and is provided by the CollabNet YUM repository. The version of the Subversion server is maintained at the 1.6.x level for existing versions of TeamForge.

Future releases of TeamForge are expected to update Subversion to the 1.7.x release. However, if you are using TeamForge 5.4 or later, you can connect a Subversion Edge server to TeamForge as an external SCM integration server; using Subversion Edge, you can install the latest version of Subversion.