There is a wide variety in terms of quality for the Toodledo apps out there. Toodledo’s own app had never given me any problems, but for those liking workflow and UI, they’re looking elsewhere. I just used Appigo’s Todo, and did a full sync and I think it deleted all of my tasks except 1. I can’t be sure because I was just testing it and had stopped using it for a week so I don’t remember what I had done prior. Then there’s Taska that’s just horrible with syncing.
None of this is Toodledo’s fault of course (unless your syncing API could be improved to be easier to use?). But this brings up a practical issue: poorly syncing 3rd party apps. Toodledo already has a way to export your to do list, but how about implementing an automated one that backs up 1 or 2 days of tasks and notebooks everyday? If data is corrupted or an app bug deletes a to do list, then we would be able to grab a previous backup. And how about a logging feature that displays exactly what a sync did?