It's not just 'back-end' and 'front-end', there are many subtle levels and tasks which need to be tightly integrated:
Matching engine,
Database persistence,
Caching,
Api core server,
Bitcoin/alt-coin RPC back-end,
Web sever,
Front-end website
IMO you can't really have several separate teams work on these parts, they have to be very carefully designed to integrate together otherwise you will have a giant mess on your hands.
Cheers, Paul.
Most of the items are for a back-end. U
can have several teams if u have a protocol. But I agree that everything should be very carefully designed.