It sounds to me like you might have accumulated way too many zip files, based on your comment about how long the sync takes. You can check this by going to the directory in your iDisk where you've told OmniFocus to find your database (by default, the Documents directory), selecting the OmniFocus.ofocus file, and right-clicking on it to bring up the contextual menu where you will choose Show Package Contents. My guess is that the number of files in that directory is going to be very large.
If that turns out to be the case, and you are confident that the desktop version's database contains all of your data, you can force a compaction by following these steps:
- Go to the Sync preferences pane in OmniFocus
- Show clients
- Unregister all of the clients
- Set the sync method to none
- Close the preferences window
- Do File->Compact Database
- Go back to the Sync preferences and set them up again as before
- Click the sync button. If asked which version of the database to use, you want to use the local copy.
- Now go sync your iPod. When asked which version of the database to use, be sure to specify the server version.
Another possible cause for crashing during sync is if you've got some large attachments in the database which are causing the iPod to run out of memory. You can check on this in 1.6.1 as above, doing the Show Package Contents on the OmniFocus.ofocus file on MobileMe. Most of the transaction files you'll see will be small, 1 KB seems to be typical. If you see multiple files of 100 KB or larger, you've probably got some embedded files (there will be 1 large file with a name starting with "00000000" but that is expected). Unfortunately prior to the 1.7 Sneaky Peek releases it is a bit tedious to track down the large attachments; you can either send your database to
omnifocus@omnigroup.com and ask for their help, or see my posts
here for instructions on how to attempt it yourself.
If you have any doubts about how to do these steps, by all means contact the support ninjas at the address given above, or by telephone (see the Omni website) and they'll help you out, but they don't currently work on the weekends, or outside of normal business hours in the Pacific time zone.