Just a thought, but I think using the keggle w/ the smallest opening on the MLT would work best. Using a pump I move strike water from my HLT to my MLT at wide open pressure but recirc and drain from my MLT into my BK pretty slowly. Why not use the bottleneck where you don't flow wide open anyway?
Kegged: Hoppy Amber, ESB, Weizenbock, Breakfast Stout, IPA
Fermenting: Yooper's Oktoberfest