At what point does this potential save-bug happen? Right now I've reached World 4 and I have all of the Electoons and Skull Teeth up to that point.
You'd be well advised to back up your savegame now, if you haven't done so yet. I think it happened to me after the third world (and I didn't know about that bug beforehand, so all progress was lost), but I assume it can happen anywhere. Maybe you're lucky and it won't happen to you, but if it does you'll be sorry.
I remember someone from Ubisoft commented on the bug in some forum and advised to completely delete all files in your savegame folder if it happens, for a clean start. They didn't say a word about making backup copies. They also put the blame on the system of the affected users, to the effect that it's probably due to antivirus programs running in the background or something like that. IMO, the most important reason why this bug is so serious and game-breaking is a flaw in the game design though, and I'm not even talking about the technical side that makes the game vulnerable to save game corruption, but about the decision to only allow automatical saving to one save file per profile and then not even have the game make a backup copy of it.
I've wrote a bit of criticism about the game, but this hasn't been included in it. I'll leave that criticism out of this thread and post, even though I'd like to think that it could properly fit in with a looser interpretation of 'has Origins been fixed for the GoG release'.
After reading this thread I backed up my save file. The first time I did so I didn't copy but cut it from the appropriate folder and loaded the game to find no save file. A quick look found the save file and I copied it back to the appropriate folder without any issue. Each time I end a play session, usually after the last level in a world or the first level or a new world, I make a copy and put it in the Documents folder or on the Desktop itself.
I'm pleased to see that I haven't lost the save file from the appropriate folder once and that I haven't had a problem with using the back-up file. When it comes to the mechanical design of Rayman Origins I find a lot to criticise (the art, music and environments are just gorgeous and thoroughly beyond reproach) and this potential issue doesn't due Ubisoft any favours. Situations like this make me wonder about QA because, let's face it, QA in the gaming industry seems to have been all but relegated to paid beta-testers (read: people who pay to have beta access and ultimately end up testing the game). I'd like to see this trend reverse for companies that have already cut their teeth and have some real clout, as they can afford the extra time and we should expect the extra time. We shouldn't have to make back-up saves.