See debdiff attached.
libx11-6 dependency is moved to suggests.
I tested the finch package without X (in a chroot), result: it works, except an annoying warning saying it can't find dbus. It goes away by installing dbus... but dbus installs libx11-6. Given that it is only a warning, and doesn't seem to cause any problem using finch, I just suggest finch 2>/dev/null.