I doubt that there'll be much new footage (scene wise) for MOS since the only major scenes that were really cut from the film were the Kents taking a baby Clark to the hospital and Lois being interrogated by the military (before Superman had shown up).
From what I had noticed from watching the BTS features from MOS, it seems like Snyder just mainly trimmed down a lot of scenes, where he just took out moments from an ongoing scene in order for the film to be more well trimmed and tight.
I mean would seeing shots of Clark leaving the church or an extended shot of Lois running out of her apartment be that much of a difference maker?
Now if Snyder had filmed scenes that took place during the final act of the film, or anywhere in the 2nd half that were new scenes in general....namely character building scenes, then I think an extended cut would make a difference.