My son attended "multi college ID" when he was a freshman. At the time, he played for DA, and he often played-up to older age teams. So, I noted it to the camp organizers, but the camp devided players into two groups based on their grad year, and my son automatically went to the younger group. I felt the coaches didn't really pay attentions on the younger group side, even though my son dominated at the scrimmages. I also found that most of coaches in the camp were assistant coaches, and there are very few D1 head coaches. At the other hand, my son also attended real ID run by each college. At these camps, although my son started from the 2nd group with Fr and So, but the end of the camp, he was in the main group with pretty good Sr. and Jr. players. The head coach also spoke to my son in person, and I received a follow-up email.
For me, multi-college ID for Fr. and So is just for usual commercial summer camps everyone can join. It is not really elite ID camps. I do not know for Jr. and So., but I would like to go "real ID" run by each college.