I am using the bean-animal overflow from my refugium to my display tank. The siphon and open drains go to the display, the emergency overflow goes to my sump. During my freshwater test of the system the bean-animal system is quiet and once the siphon was established I saw no bubbles entering the main tank from the two drains that go to it.
I do have issues getting my siphon line to start. I think that because the refugium tank is only around 8 inches higher than the display tank, I may just lack head pressure to dislodge air and get the water flowing into that pipe initially.