For those who are experiencing problems when trying to sync to "/Android/data/com.bittorrent.sync", I'd like to share the solution that fixed this for me: I had a folder "eMagazines" on my SD-Card I used to sync to my PC before installing KitKat. After the installation it didn't work anymore. So I moved the folder to "/Android/data/com.bittorrent.sync/eMagazines", selected it as sync-target in BTSync, but still got an error about no being able to write (I used ES-Explorer to move the folder). This happened despite having the Tablet rooted and having installed SD-Fix. I moved my magazines-Folder back to were it was before and used the "New Folder"-Function in BTSync to create a new folder "eMagazines" inside "/Android/data/com.bittorrent.sync" resulting in the exact same path as above, but working fine. I then moved the contents of my old eMagazines-Folder to the newly created one and it works like a charm. I strongly suspect that the insufficient rights for the folder are somehow moved along with it, preventing the folder to be write-accessible for BTSync despite being in the right location if you move an existing folder. This should also work on non-rooted devices without SD-Fix. In that case, I'd suggest to create the new folder as described and then connect the SD-Card to a PC to move the files from the old folder if you don't have an Android filemanager that has full access rights.
