I think I'm going to stick withe the standard hard-copy from either play.com or amazon.co.uk. I need to check with play to see if they get the Greek factions DLC. Shipping with play.com is free and they usually send items (Games, movies) out so they arrive on or before the release date.
The collector's edition does not seem to add much apart from more bits to clutter up my flat.
The downloadble version (any version) is more expensive than the DVD-ROM.