Soundstage may not be necessarily better but it can reflect the spaciousness in the recording if it's there. It's probably the difference in presentation that makes it seem more capable to me on live recordings, regardless of whether or not it actually is.
But like they said above, I think the main issue is your source. There's a noticeable difference in sound quality and soundstage when I switch from my ipod classic and macbook. The macbook is better all around. And I think part of the reason the W5000 doesn't suffer from the same problem in soundstage as the LCD2 is possibly due to the bass. Bassy sound signatures tend to take away from the sense of soundstage and air, but probably not always, depending on how that balance is made. If I remember correctly, the W5000 doesn't have loads of bass or sub bass like LCD2.