pg_dump compression; Server or Client side
Solution 1:
The compression with -Fc (custom format) dumps is done client-side. Per the documentation:
This format is also compressed by default
There is no protocol compression done between client and server.
PostgreSQL protocol compression would be very nice to have, but hasn't yet been implemented.
You can run pg_dump server-side and stream its compressed dump over something like ssh to the client if you wish, though.