This will not work for everybody!!!
Check into things before you use the all.dat file from folder '2' as your backup option. I saved it, and then uninstalled Opera, so i could install it to my storage card fresh, rather than moving it. I replaced all.dat in new location, and ALL my bookmarks are gone...and I had a lot. I'm kicking myself for not verifying before the uninstall...so all versions or devices or something are not the same...I will post when I find what happened and how to avoid...just wanted to get the warning out there.
So copying all.dat to my laptop and renaming to a .txt file shows that it does contain my bookmarks amongst the garbbled characters. Opera just doesn't use the data. Everytime I run Opera it replaces with a fresh all.dat file of 500b. The only difference is the install location...same version from the same original cab file. Any ideas how to force Opera to use the data in old file rather than replacing it with empty new one??
Another side note which I'm sure is obvious to everyone but changing that dat file in anyway while in the text editor makes opera crash forcing a reset...followed by over 25 error messages to go through upon boot up....so I would recommend not trying it as I foolishly did!