That being said there are times when I think you also have to keep in mind personality conflicts that might happen. I've had a few kids over the years that do better with my assistant, and the same was true when I was an assistant. It takes a lot for me to remove a kid from the program because sometimes they need band more than anything. I just won't let them hold back a group of motivated students with their behavior.
If it's making you wonder if you should do it, do it. You can always bump them back up if you feel like the message was received.