Im asking because I own the "Sold out Software" version of broken sword 1 and 2.

they come on 2 cd's each, while on gog bs 1 original is 271mb. was quality lost or does the installer expand a lot?

Would be nice to get a detailed answer to this.

The installer for the original 275mb but once installed its 422MB.

And the big reason its smaller then the original is because the original game used WAV audio which is a uncompressed audio format which made the game file size a lot bigger, but because of ScummVM support was added for compressed audio formats, so GOG have converted (encoded) the WAV files into OGG which makes them a lot smaller without any big loss in quality (there is a slight difference but you most likely won't hear it) Also the movies are in a different format from the original video which will also makes a difference in size,

So Anyway to answer your question the original version of GOG is the full game in pretty much the same quality as the original CD's, the audio has been changed but you probably won't hear the difference.

Yeah if you have the original CD you are fine, And if you ever want to make the game smaller you can always grab "ScummVM Tools" which has the tools to convert the WAV to a compressed format for Broken Sword, you can even compress the audio into a lossless audio format like FLAC if you prefere, its still smaller then WAV then and no quality loss.