There are two how-tos of interest: Backup Plone, and Repozo.py.

My process so far. Incremental backups work until the DB is packed.

ssh into the server

run the repozoBackup.sh to create new incremental backup files

sftp to the server

cd /path/to/received/files

sftp username@example.com/path/to/files

get *

download only the new incremental files into my local webapps\zopeDataBackup

To restore locally:

Stop Zope

Go to webapps

run repozoRestore.bat

start Zope