OK, I'm very much in the market for a 2008 Acadia. I have seen some info that states the navigation has voice activated commands if purchased with the Rear Entertainment System. Can anyone clarify that please? What kind of commands are available with voice activation? Is this only if you have purchased the rear entertainment? Is it not available with navi only? If so, that seems kinda strange to me. I haven't been able to find anything to confirm. Thanks!