Nothing is final until the game starts, so I can adjust it right now if wanted.
If you have them off, it focuses the game imho, but reduces your margin for error, because you only have so many settlements.
It makes influence more important early on, to grab those settlements, but less important later on, as there are no settlements left. That said, you’ll always want influence for the NPCs.
I was a big proponent for colonisers off, and pushed hard for it to be included as a game mode, as IMHO it just feels more natural, plus I think the ensuing restriction on players makes the game go quicker, because you may realistically acquire 4 or 5 colonies peacefully, and then you’ll be obliged to go to war.
Not so relevant for our game, but the AI seems to stabilize at about 5 colonies anyway, so this should shift their focus onto war-fighting.