The actual problem for me of having 6 is a question of difficulty/rebalance, still not answered sufficiently in hundreds of posts. The most common answer seems to be, "let difficulty as it is" and use the usual settings (like Story Mode, Easy, Classic, Hard, Masochist, Real Man, and so) to overcome the consequences of having 6.
There's a saying among DMs: "If encounters are too easy, just add more goblins." Larian could just add a couple more foes to the encounters. Now that Larian has implemented the Swarm AI, longer turn times is no longer an issue. So I don't see the difficulty in balancing a six man party.
