I do both, so I guess we're pretty well integrated.
It leans more towards a mutual existence than an integrated relationship, but really it depends on the topic/event/or discussion. We both poor a lot of intensity into our ministry areas, and it leaves little energy left to move beyond the scope of our job description.
I thought I'd ask the Student Ministries guy before I answered...and we agreed that we have an integrated partnership! We both lead ministries at multiple campuses with the same mission...to be used by God to change lives. I have great respect for Brendon both personally and for what he does. I know that he is all about seeing kids ministry win.
We currently have an interim youth minister, but prior to that we had a very fine youth minister. For the first 6 years she was a "volunteer" and the last 8 years being paid on the church staff. Not only were (are) we good friends, I believe we complimented each other's ministries. She would volunteer for children's events, and vice versa. We agreed on pretty much everything, including that 6th Graders should be seperated but yet still in the children's ministry. She was a great, mature, Christian youth minister in very sense of the word. My family and I have only been blessed by her presence in our lives. I do know this is often rare and feel for the churches and ministries that have other outcomes.
The last youth pastor we had proved to be difficult for me, because he demanded (that's exactly the right word), the no youth would participate in children's ministry during either hour, because "they need to be in youth group first hour and worship service second hour." This went against everything I believe about how important it is for youth to have real opportunities to serve the church while they're still here, so that they'll stick after high school!
So that pastor left (he had other problems, too). The one we have now has been wonderful. Fresh out of seminary, but very mature. Has handled a number of delicate issues with parents very well. We went to an Orange conference together last week, and have been discussing ways to partner. He believes the youth need opportunities to serve too. Praise the Lord.
So actually, my vote 2 years ago would have been "dysfunctional", but now its integragted ministry partner!
Good luck with your research.