Complex sentence: Although it is more expensive to hire, train and retain such personnel, the advantage lies in their flexibility; they can respond on their own to any number of rapidly evolving situations rather than waiting for the arrival of other specialized personnel.
Split into simpler sentences: Although it is more expensive to hire, train and retain such personnel, they have a clear advantage in terms of their flexibility. They can respond on their own to any number of rapidly evolving situations rather than waiting for the arrival of other specialized personnel.