| Taroot |
In our game (~75% History of Ashes, 4 member 10th level party) we also use medium xp track. And for that place game still look nice balanced. I just start wonder how SoS will be work with 11th level party but - no brain, no pain.
Individual chapter's work pretty nice, even if party was one level "weak" then game engine provides. But if you wanna more xp, then between parts it's so many oportunities to "put in" more content. Best for was Kaer Maga where party can at least get close to 10th. And in story like CoCT Ad Hoc and "roleplay" xp fit's great.
But if You wanna to your game be challange for players - don't bother yourself for that until HoA. Then You can add some side encounters (ah, Cinderlands hazards ;) ) to "cathc up" right level.