fisk0: GamersGate uses online authentication for the installer (you have to be connected and activate the game against their servers during install), after that I think it shouldn't be anything unusual.
Pretty much comparable to Steam in that aspect though.
You're thinking of the downloader. Which actually makes it more comparable to GOG in that regard. Anything in the actual installer that requires authentication was put there by the publisher.
The only real downside to Gamersgate's DRM-free games is that the downloader deletes the installer once you've installed the game, regardless of whether or not you choose to keep the rest of the files.
But that's easily overcome by copying the install directory to somewhere else when the installer starts (or at least before you close it).
Namur: I'm planning on getting the series here once it's complete, so here's hoping the extras situation changes by then.
Well, let's hope you're not waiting too long for the soundtracks.