When we weren't sure if our team was going to make it, we strongly considered this option. DD liked the idea of playing with several teams over the fall and choosing one for spring. I don't think she'd want to do it long term. She likes bonding with one team. But if your player is in demand why not do this? It seems like a great way to get some good exposure and experience. Also to learn which coaches you might consider playing for and which are no way.
We considered this one summer as well. DD has guested for several teams over the years and it seems like someone is always looking, so I am confident she would have had plenty of work. You just don't always know when or where. And like your DD, my DD also like to bond with her team. She has spent most of her travel ball career with two organizations and still has close friends from both. Even some she has not played with in 3 or 4 years.