Trying to force someone to stay longer than they might like is disrespectful as well. 6 runs is about an hour. That's about as long as you can expect to keep 7 random people. Want anything else, form a static and go with 8 people you know.

Yes, I know your argument is going to be that you specified staying until you get your item. That's just not reasonable when it could be 10-20-30 runs before everyone gets their item. It's different if it's something like Ravana/Bismarck where everyone will get their item in a maximum of 10 tries. I've done A4 numerous times and have only seen the torso item drop one time. What if everyone wanted that one piece and your group had the same luck as I've had?

My advice? Suck it up and stick with 4 and reform. Let anyone who wants to stay because they haven't had their drop or they're farming Esoterics stay.