We had to send them back before we really got to test them well, but I will just say my daughter has broken two ghosts in the last 15 months and both times we got new ghosts. The Marucci didn't enter the conversation.
It is odd that Core had that experience because I have two demo Echo Connects arriving tomorrow. They emailed me (16u travel coach) out of the blue and asked if we wanted to demo their bats. We are looking forward to seeing how they perform.
My daughter didn't report any vibration problems with the Marucci, she just didn't feel like it had the pop of her Ghosts or CF.I can just tell you from my experience using my son's CAT8 aluminum. It is like a cartoon running into a brick wall. Heavy vibration. If the fastpitch is anything like that then girls will probably hate them.