Andrew - there is not alot of difference in output, although the middle has a slight drop - hear the clip i've posted for you in the Players section (recorded in true Seymour Duncan style - a short indistinct bar) - the first two bars are a Mule Alnico IV bridge, then the same in the middle and then an Alnico IV Mississippi Queen.
All controls on the guitar were at 10 and the 'amp' was the Soldano model on the Guitarport.
and don't slag off my playing, coz I know its s**t