Before, you used to be able to put up a Deed, enter the mission selection map before the other player(s) accepted the Deed, and once everyone had accepted and the portal opens, you could start a different map and difficulty. When the mission then starts, you would still have the Deed modifiers, but would be playing on the difficulty and map you chose after the Deed.
This no longer works when the Deed belongs to a client. The map does not get the Deed modifiers.
It does work if the Deed belongs to the host though.