[coopdog]

Integration with the small couriers systems would be a problem. You'd probably have to design the thing end-to-end then get them to migrate

(note: I'm only just discovering EDI, it might be thai this isn't as big a problem as it appears)

[onlawschool]

I don't anything about couriers' systems to have an idea whether or not it would be feasible to build something that integrates with them (or how difficult it would be to design one end-to-end).

If you could design the thing end-to-end, I wonder if switching barriers would make adoption difficult.