Sync Toy is unsupported, period. It's a tool which Microsoft developed, but which you use at your own risk.
Personally, I don't use Sync Toy at all. Instead I use robocopy or richcopy plus custom shell scripts. Robocopy is built in Vista and newer Microsoft operating systems; richcopy is another unsupported Microsoft tool but a lot of people find it easier to
use than robocopy. Either one is more robust than Sync Toy.
I'm not on the WHS team, I just post a lot. :)