So that's seven taps, including the outlet valves on each vessel right?
I'm still setting up at the moment, but I spent a lot of time pushing around drawings to come up with the minimum number of taps to get the job done. I'm going all stainless, so taps are expensive. Here is the final layout. I'm afraid it will only work if you've got a reversible pump - I'm building a peristaltic pump. I'll have a cheat sheet somewhere with the settings for different directions. Taps which should be on are specified, if pump should be on its direction is given:
Underlet (HLT - bottom MLT) : A,B,D, P-> (can't gravity feed through peristaltic)
Overlet (HLT - top MLT): A
Recirc (bottom MLT - top MLT): B,D,<-P
Sparge (Bottom HLT - top MLT, bottom MLT - boil): A,C,D,P-> (A can be independent of C,D,P-> for batch sparge)
Cube (boil - cube): C,<-P
The HLT and boiler are on the same level, MLT is below them. Cube can go anywhere. Pump just has to be lower than the sparge inlet, or lower than the underlet if the pump doesn't self prime. The hose to go out to the cube has to pass higher than the top of the level in the MLT, it has the added benefit of acting as a snorkel to indicate stuck mash when recircing or sparging.