In more than one place I've seen a munter/mule combined with a prussic as the ratchet point in a pulley system, especially in one of my favorite books:
http://www.amazon.com/Glacier-Mountaine ... 0762748621
It's hard to make out if that red cord is actually tied as a munter on the end but I think this is an example is here:
http://www.summitpost.org/ratchet-syste ... ing/700714
But even the Glacier mountaineering book shows multiple OTHER illustrations of just a simple prussic or even an auto block with no munter/mule.
My question is, is the adjust-ability worth it over a prussic on a simple loop? Creating the prussic hitch is a PITA when you've got 8 ft of rope hanging out the other end and it just takes that much more time while somebody might be dangling in an icy crack. If you do need to back it down, can't you just have your third mind your prussic and let it slip as the hauler back-peddles?