[calumma]

Removing all attachments (there were a few!) has enabled me to successfully get the database onto my iPhone 3G. Follow-up syncing nearly works as well. Whilst the sync is successfully initiated and appears to complete (although relatively slowly), the iPhone still drops my wireless connection towards the end of the process.

I'm using an Apple Airport Extreme. What's interesting is that the wireless signal drops on my iMac at the same time as the iPhone, suggesting the Airport Extreme is struggling with the connection and dropping the link? The iMac immediately reconnects, the iPhone only reconnects if I manually select my wireless network in Settings. The iPhone will also automatically reconnect if I exit OmniFocus and use any other network application (such as mobile Safari).

Not a complete solution for me then, but the application is at least usable again. Thanks again whpalmer4 for the tip on stripping attachments.