Tresorit currently does not support the partial synchronization of Truecrypt containers: when you add a new file or modify your Truecrypt container in any way, Tresorit will re-encrypt and re-upload the whole container.
Instead of TrueCrypt, Tresorit recommends using Bitlocker or FileVault to protect files locally on the device.
Tresorit encrypts all files at the client side before uploading them to the cloud, so you get the same, high level of security as if you used TrueCrypt. Only people who you share your files with can access your data. Not even Tresorit can view it, which is one of the reasons there is no password recovery option.