The following unerase tools were tested:
With a small number of deleted files, all the test results were indentical. All the files were recovered, and the difference in speed was negligible.
Speed was tested with two million deleted files.
It is impossible to estimate speed or recovery quality because the tool displayed an error "out of memory" at 43% of the scan, so we do not recommend it when you need to unerase a large number of files.
The preview button, which does exist, seems inactive (unavailable) at all times.
Typically, if you need to recover a few deleted files, all unerase tools get the same result - recover files with the same efficiency and speed. The choice of a recovery tool depends on: price, ease of use, and tool's interface. In case of deletion of a large number of files (starting with tens of thousands), unerase becomes similar to unformat. When choosing a recovery tool you should take into account what recovery capabilities a particular unerase program has. For example, Recover Files cannot handle two million of deleted files displaying an "out of memory" error. Recuva has a limit of about six million deleted files on NTFS and just hung during the scan requiring a hard reboot of the system.