[url]http://arstechnica.com/journals/thumbs.ars/2008/04/16/study-suggests-game-demos-are-bad-business-for-publishers[/url]
Ars is reporting on a new study that shows that games with demos sell fewer copies than games with out them.
Unfortunately, the study is not available to the public, so it can't be scrutinized.
My thoughts are, of course they will sell fewer copies. A bad demo will turn most people off of a game. Demos have the risk of either showing off the great parts of the game, or exposing all the dirty flaws.
Trailers don't have that. They can be taylored to only show off the good bits.
If publishers follow this studies advice and ditch demos, we will certainly see some angry gamers.