OK, I finally go this to work...

First I did this:

http://www.howtogeek.com/howto/ubuntu/how-to-share-folders-with-your-ubu...

Which led me to this (to install the tools on the client):

http://www.howtogeek.com/howto/ubuntu/install-vmware-tools-on-ubuntu-edg...

Then I soft-linked the mounted folder to /srv/repos/svn (removed the svn directory first)

And all is well with the world: I can perform my backups from my host and the client is using the folder to support svn.