DataTransferManager available to Windows Phone 8...
The major hurdle with the DataTransferManager is that it's only available to native applications. Whiskers was developed with C#. Thankfully I won't have to port from C# to C++. I can develop and run with mixed code if I develop a Windows Phone Runtime Component that interfaces the native code stuff with the managed (i.e. C#) stuff.
The other issue is that this will mean forking versions of Whiskers. One for WP 7.x with the current Backup and another new version for WP8-only with the new Backup. I'm not thrilled with forking and maintaining two versions but you get what you get and MSFT has provided the sandbox we must live and play in.
I found a good article and starting point on this stuff here. I'll be working on this during what free-time I have and hopefully (yes I know, hope is not a plan!) I will have something to share and update Whiskers users with a new and much-improved Backup feature.