A few weeks back Gossamer gear sent me a new Gorilla as I ripped the rear mesh pretty badly on my original. They said they would repair but decided to replace with a new one....just recently I opened it up and noticed the pack was a new design.....a few changes Inc a removable brain with a drawcord synch to close main pack body, lil whistle built into sternum strap, more padding on shoulder straps and stiffer reinforced waist belt....I've never owned a pack with a brain so trying to decide if I'd have a use or not??? I guess it's useful for colder weather use as could put gloves, beenie, buff etc inside and should stay drier than back mesh pouch...anyone else try out new Gorilla yet?