Errr, it worked? I surely hope that 'normal' OSX user does not operate with root priviledges. I mean, too easy to screw up accidentally...

If I remeber right, I was actually root at the time. If a normal user did this, it should just delete their home directory, and if an admin does, they could potentially screw up several things, like installed programs.

Regarding those 'protected' CDs, what is typical reaction of shop staff when you return them?

I've only had one incident where they flat out refused to do anything except exchange it in the initial discussion. So I did, and will be back later to get the refund. All the other places refunded it once they saw the sticker.