Most aircraft like that have an STC that brings them back to 9 or less and most 135 companies operate them 9 or less. I know the Caravan is type certificated for something ridiculous like 14 people, but in commuter service most run 9 or less due to the difference in operating requirements. On-demand is different though. Once you go 10 or more, there are many more regulations that have to be complied with. Not sure how this all affects it, but those would be the issues I'd delve into for further research.