BT sync with my 8700r works perfectly.
I had to pair the BB to XP with the XP BT wizard, then go into the Blackberry Device Manager and "Enable Bluetooth Support" and then Confiigure Bluetooth.
Once that was done I went into the Options > Connection Settings menu on the Desktop Manager and chose the BT connection.
For some reason the Sync didn't work properly for me the first few times, it kept giving me an error the the desktop couldn't read the data, or something like that.
But I've synced it a few times today and its worked fine.
NOW, if only I could figure out how to get the modem working over the BT connection. ;)