Hi there. A new version - 2.5.1.26 - was released recently.
Download link

Features.

- Block Level Backup.
Finally files that changed a little don't need to be reuploaded as whole files.
You can set up a schedule for Full versions (and we strongly recommend to do so) and a schedule for Block versions.
Some infographics in this Blog article.

Important things to note:
1. Block Level in Mac is based on a more advanced mechanism than that of Backup for Windows - and thus they are incompatible. Full versions of files made by the Windows app should still be available for restore in the Mac app, but not vice versa.
2. Retention policy by number of versions ignores Block versions and only counts Full versions. This contradicts the behavior in Backup for Windows.
3. Files of less than 10 MB size will always be backed up as Full versions, same as in Backup for Windows.

Points one and two are subject to further improvement in Backup for Windows.


Bug fixes.

- Several hanging backup plan cases
- "Parameter count mismatch" after upgrade from older versions
- Many minor things such as tooltips, text alignment, some functionality previously missing in some UIs and so on.


Logging.

- Logs of High (INFO) level of verbosity now specify why exactly a file is purged (DeletedLocally, NumberOfVersions, RetentionTime - named after the respective rules in retention policy settings).
- Minor improvements and additions.