Presumably a lot of this is out of date, so these notes may be of limited use, but these are my thoughts having MC'd a five player game last night.
With five players, character creation took far too long. Working out holdings, generating back stories and binding the world together took most of the evening, which appealed to some members of the group but not others. Overall, less choices for holdings, ie: larger groups of connected holdings (A busy port town, a great castle, and a wild woodland OR a walled market town, a hillfort with a palisade and rich farmland OR mountains, hills, wild clans, fertile grazelands and a great wall manned by staunch defenders, etc) just to streamline the creation process. There's always the blank options for people who want to mix it up.
The playbooks all feel too rich, like everyone bringing a mud cake or gateau to a pot-luck. Each of the available books presents an independent character with very strong flavour and obvious personal goals. However, they all pull in different directions, making player interaction difficult to achieve without forcing them into place. We had a similar problem playing Apocalypse World in our regular campaign, with some of the player characters just drifting away and losing relevance, putting pressure on their players to find more and more reasons for them to stick around. In a two-to-three player game, where the MC can focus more heavily on each of the characters in turn, I can see this working, although in a 'wait your turn' fashion as the Dragon Herald manages affairs in her keep, the War Herald ravages the countryside with his band and the Outlaw Heir rallies up support for her cause, but with the Wicker Wise and the Troll Killer in play, someone is always feeling left out, bored, texting at the table, waiting for their turn to do something. Because each playbook is so dense, it demands complex stories be told. Before character creation was even finished, we had a huge cast of NPCs for me to get to know and keep track of, personalities to develop and embody. It was hard, and as MC I kept stumbling over the details.
Our group has played tremulus, Monster of the Week, Dungeon World/Grim World, Sagas of the Icelanders and Apocalypse World. The players prefer Apocalypse World because of the flavour, the starkness and the sense of danger in combat, but our next campaign will be tighter focused, the players selecting members of the Operator's crew (Gunlugger, Battlebabe, et al) and acting as a sort of commando A-team for the hardhold established in our last campaign. They've decided on this because with that group size, playing with a hardholder, tribal leader, Maestro D, Savvyhead and Shieldbearer, there wasn't much co-operation possible in the group. For the most part, when shit needed to be done, the characters were so powerful they had other people to do it for them, or wouldn't be doing it together. I had people play through their NPCs, gangs, et cetera, but it didn't sit well with my players.
Sagas of the Icelanders was a revelation to us all, with the concept of linchpin playbooks. The Man and the Woman are the centre of the action, with the other playbooks revolving around them like satellites, informed by their choices and shoring up their weaknesses with various different kinds of strength. Each of the available playbooks for AW:DA is a linchpin playbook, giving everyone the strength, responsibility and depth of a primary character. With a larger group, this translates to four out of five people sitting around, waiting for their turn, while the current PC interacts almost exclusively with the MC unless a suitable situation is contrived to bring them all together.
For larger groups, I would suggest only one or two linchpins. The Dragon Herald and the Outlaw Heir, for example, would work well as diametrically opposed personalities, with remaining players divided between them into two rough teams, working against each other on opposing sides of an epic conflict. The Outlaw Heir and the War Herald could work as two linchpins on the same side, but with vastly different approaches to conflict, with the players divided between the Outlaw Heir's champion, advisors, magicians etc, and the War Herald's lieutenant, specialists or engineers.
The oaths felt unsatisfying and did not inform character relationships as much as we had hoped. A larger selection of oaths, or some that aren't counter-intuitive would be ideal. The Troll Killer, for example, could swear to protect someone's holdings from monsters, or such. I realise a blank option is present, but for the most part, the oaths didn't make the group feel bound together by solemn promises sworn in blood, upheld to the death, they felt they were filling in blanks, hoops to jump through to mark that experience check-box. Oaths should be binding and important. A sworn oath in the dark ages was pledging a life. If the Troll Killer has sworn to seek peace instead, that character is effectively crippled, all their cool equipment except the stealthy stuff is for nought, because if thet commit violence, they are an oathbreaker, scorned by men and made a pariah. To break an oath makes a person dishonorable, untrustworthy and cursed by the gods. Oaths should tie the players tighter than flesh, breaking one a terrible choice, and the conditions and consequences for doing so dire indeed.
Perhaps there is still a place for Hx, Relationships or Bonds (whatever), as well as oaths. You can have good ties to someone without having sworn them an oath. Perhaps one to three oaths per character, each of them huge and binding, and actual relationships determined through Hx, bonds, or the like, to tie a group together or wedge it apart as suits the situation.
My group is comprised of inexperienced roleplayers who have come into the hobby through this indie renaissance. I love telling a story, and they love the level of agency and control they have in the *World systems, the elegant simplicity of the rules and the narratives we generate collaboratively. However, because we are inexperienced, have only been playing for seven months or so, there are still awkward warmup times at the start of session before people lose themselves in the game and flow with the story. The rigours of character creation, the implied force of their personal goals and the different directions the oaths pulled them in contributed to an extremely slow start and eventually a sad fizzle as everyone sat around the table trying to figure out what to do. The Troll Killer wanted to go to his mountain lodge and hunt for trolls, the Dragon Herald wanted to be involved in politics back at her keep, the Outlaw Heir wanted to lead the War Herald to do battle for her crown but he wanted to mind his village and mob of bandits. The Wicker Wise wanted to sit in contemplation of the bird gods, and short of throwing a troll at them, or a squad of enemy soldiers, I wasn't sure which direction to go. Having thought about it now, ideally I should have had Baron Whoever kidnap the outlaw heir and have the characters chase off in pursuit, but by the time we got to playing, the entire evening had gone and we were all exhausted.
The Wicker-Wise's ability to perform a ceremony during a lull in play or between sessions without a sacrifice gave that player license to use magic (which I saw as terrible, dangerous, and to be respected) lightly, twisting the spells to provide a charlatan’s light show. 'Fine,' I said. 'And what will you sacrifice? What will you give up to perform this thing for amusement?'
'Nothing,' replied the player. 'I prepared for it during a lull, and there is no urgency here.' For magic, there should always be sacrifice, and for the charm or ceremony to be performed with urgency, the sacrifices should be immediate, visceral and have lasting consequence to the Wicker Wise personally. If the Wicker Wise is cunning, and plans ahead, then let them push that sacrifice on to another, terrible though it may be, but I don't think they should ever get to manipulate the fabric of reality for free.