And you think that big groups will not have one or two with scout profession who then will do the same like now?
If you have enough players (10+) which are separated to groups by the entrance preview and you have voice comm, you get realtime info about the situation in the city. So there will be difference in amount of information you get, if you implement this change.
PvP is now more about waiting over cities. Waiting on enemy first step. Sometimes you are waiting many minutes because of gang on world map has bigger advantage over the gang in the city.
But i dont want to ruin game for non PvP players or single players. You can get perk scout on 3rd level, where many others are unusefull. Maybe everyone should use preview but with big cooldown (15 minutes) because of existing characters, but perk scout will reduce this time to reasonable timeout.
I.e. without scout perk.. one preview in 15 minutes (real time), with perk (2 previews at the moment - just because many exid grids are wide and you must watch it twice to get enough info), than wait for another 2 previews 2 or 3 minutes).
And Lexx, i heard you are experienced map maker, please, look at my different suggestion about small map modification
http://fodev.net/forum/index.php?topic=1891.0