The stats I need for the pump include dBA but also the heat dump into the coolant. As per the blue table on this page at the cooling-masters review:
http://www.cooling-masters.com/articles-33-13.html
(sorry but english converters are banned at my work so no English URL)
the ratio of watts consumed by the pump vs watts dumped into the coolant varies from between 56% (MCP350 aka Laing DDC) to 82% DangerDen CSP Mag.
In my approximations it is often the case that extra heat dump outweighs benefits from flow rates, making the MCP350 one magic little pump.