I've experimented with reflex on both the flaps and ailerons.  As a result I've reflexed my ailerons about 3 degrees up and can reflex my flaps to a maximum of 10 degrees up. 

 

The best speed I can achieve seems to be with the ailerons permanently reflexed at 3 degrees and, on average, about 7 degrees flaps reflex - dependent on GW and CG.

 

When flying solo with a total of 30 gallons onboard and neutral elevator deflection, if I "trim" the flaps so that I don't have to reposition the elevator from the neutral position, I end up with around 7 degrees of reflex.