All version up to ATI 2012 Home, did not recognize ext4 partitions, so they were backed up sector by sector,
which means the entire partition.
However, with ATI 2012 Home, you can now backup ext4 partitions and only the used sectors are backed up.
Incremental and differential backups now work as well.
If you want a non-windows alternative, then use Clonezilla. I use clonezilla via the bootable PartedMagic disc, as
you can use scripts this way.