Yes, it is entirely appropriate that if the sync doesn't work that the database be rolled back into the last state. If that isn't integrated into the product, adding disclaimers when the product runs to make sure you have a good backup would suffice. Also an option to "sync what you can" would be beneficial because sometimes the thing that fails isn't really that important.
I'm very excited about this capability. Anything I can do to help out or other questions you have let me know.