Bloodygoodgames: Don't forget they are the same people that hired a law firm to send threatening letters to gamers who may or may not have 'pirated' the first Witcher. They lost a lot of my respect when they did that, as it tells you what their core values are. A shame.
I don't see anything wrong with their core value being: "We don't put artificial restrictions to the game you buy from GOG, but if you use that freedom wrong, we will go after you.". Nothing wrong with trying to catch the wrong-doers, especially if at the same time you don't cause extra inconvenience to legit users with DRM.
Not talking about you, but many people indeed seemed to have a misconception that because GOG games don't have DRM, it is ok to share them around and pirate. I hope people understand that being anti-DRM is not the same as being pro-piracy. Well, maybe for some, but fjuck them.
Were there any false positives with those letters anyway? If I got such a letter, I would just reply back "Go F* yourselves, I haven't pirated nor shared it. Thank you.". Problem solved.
Having said that: yes, I would have preferred they would have simply sued the people caught pirating or sharing their games, instead of offering an opt-out.