Hi,
Just saw something that makes me wonder ....  I was looking at Pentair Aquatics' product brochure 
here, which list both the Quiet One and Little Giant pumps.  What puzzled me is the Quiet One has a shut off pressure at 6.49psi (15 ft head) and the Little Giant 2MDQ-SC has shut off pressure at 6.2psi (14 ft head).  This is strange as I don't think the old design Quiet One can drive any high aeration type skimmers from personal experience.  I wonder what their new pumps are like as they have a High Head version now.
Titus