I wont argue about individual characteristics being the key.

But for myself as a rule I defined that salaried team members are in most cases more motivated for a long successful releationship and care about the project more.

Also, lets not forget that when we are talking about doing a startup, core members need tobhave more motivation than just a wire trsnafer at the end of the month.

Best practices for motivating startup team members are not anything new.