as for the areas being bigger i doubt it. they pretty much programmed the game old school where the whole zone is loaded into memory good old .BSP and they have to keep everything within 256mb thanks to the PS3.
even some older games had a portal type of system that lets the area "stream" which is standard in a lot of 3rd party game engines. its loads the games into chunks and pre caches the next piece of the zone, and you have the unrealED system where it does that and only shows whats in the cameras view being processed.
even 1.0 did a crappy version of that but it just loaded the other parts of the zones when you walked in the narrow tunnels, and if someone was with you they would disappear then you see them pop up again.