Inspired from OperaFly and because it couldn't run under linux, I finnaly wrote my own Opera backup script. This will backup .opera directory located in your home directory everytime your computer is started.

#!/bin/sh
SOURCE="/home/sandal/.opera"
TARGET="/home/sandal/.backup"
FILE=`date +%Y-%m-%d-%H-%M`
tar cfzP $TARGET/$FILE.tgz $SOURCE;

I save the script as opera-backup.sh, and set the script to be executed everytime linux is loaded. I'm using Zenwalk and I do this from Autostarted Application. Here is the sample of backup file:

To restore, simply extract the tgz files onto .opera directory.

Be sure to chmod with +x parameter so this script become executabled.