I had that problem, too. But I figured out a work-around. You just have to sync your data in small "chunks". In Addressbook, create a new group called e.g. "sync". In iSync you will
only sync
this group. Move a couple of contacts to this group, sync it, move some more, sync, etc. Do that until you synced all of them. Once finished, you can set iSync to sync all your contacts.
Do something similar for iCal data. Sync just one or a few calendars at a time and restrict the dates with the "Options" in iSync.
There are some issues, though. All-day events become events with a duration 0:00h-0:00h, some contacts get duplicate entries of some data (phone numbers, email addresses etc.) etc. The problem is, that this malformed / changed data will be synced back to your mac, when you sync your phone next time. So make sure to back up your addressbook / ical data before re-syncing your phone.
It's pretty buggy at the moment, but I hope, these issues will be addressed either by Apple or SE soon.
Good luck in the mean time…
