I have gotten the X700 to work with iSync.
Sometimes there are a few issues with things like the naming of various fields (mobile, home, work etc), but the rest works perfectly.
Check out the solution here:
The quick summary:
You should know how to work the Terminal for this. If you don't, learn that first.
CD into /Library/Application Support/SyncService/501
501 is the numeric value of your username, you can find it by using the id command.
Once you are there, edit the file SymbianConduitDefaults.plist, it should actually not exist, so you will be creating a new file. Into this file, paste the following content:
<?xml version="1.0" encoding="UTF-8"?>
PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
Replace xx-xx-xx-xx-xx-xx with the MAC ID of your phone. This can be found in System Preferences/Bluetooth/Devices.
Save the file. Next step is delete all pairings between your computer and phone, and pair it again. Then start iSync and sync that stuff. The synchronization even includes contact pictures and colors of your iCal calendars! Great stuff.
I got the idea from: