We run a system where we check a drawing out from a satellite office to work on it locally, our document management system marks it as checked out and leaves a locked version for use in the office as a read only un-saveable, un-editable drawing, as soon as it's finished we check it back in and the drawing is available to all for working on.
We do a lot of co-ordination work between the offices my company has, so we need to be able to be sure everything works ok, we tried folder replication, but this was always done at night, and after about the 10th document/drawing losing changes because two people in different offices altered them we abandoned it.
Our drawing database is replicated in real time with a copy stored in each office for speed of access, so if i check a drawing out, it's locked in all the offices straight away.