It appears that the Sync Mirror delete from destination is not working on on the 3.1.0 Pre-Release -- at least on my systems. I have tested using both pre-release build 6 and 11 and get the same results.
Sync Function options:
File Checks options:
Use Recycle Bin
On initial first run in my destination location as expected I get both the a.txt and b.txt files.
I then modify the content of a.txt and delete b.txt in the source location.
Re-run the Sync.
The progress screen states as expected:
Checking the destination location a.txt is updated but b.txt still incorrectly exists. Furthermore checking the Recycle Bin and there is not a deleted copy of b.txt in there either as expected.
Have tested with both build 6 and 11 - same results. Running on Win Server 2008 R2.
I think this is a huge regression from the production release functionality. Along with this regression and the fact that you have now disabled multiple instances of Toucan from running unfortunately far outweighs the pluses of moving to this release for the enhanced Rules capabilities.