Based on the configuration of the box section of Dury Lane, I cant see why the producers would want that theatre. They must want it purely for its size (seating) unless they plan to scale down the proscenium set for Wicked (they use alot of wooden scafolding and cog wheels (i hope they dont plan to use the scaled down version that is used on the Tour.
Also dury lane has one of the biggest stages, Wicked doesnt really need a deep stage to work.
I would have gone with the Apolo Victoria, mainly because you can change the colours of the Auditorium during the show to reflect the mood, and it is a big house.
http://www.flickr.com/photos/27199361@N08/ Phantom at the Royal Empire Theatre