Here's a short video from Wings and Wheels 2010.

The BMPRA were lucky enough to have a stand and some flying slots, so we put both an F5D and F3D model up at the same time to entertain the crowds.

I think that out of a dive F5D is significantly faster, but doing the short laps they were about the same, which if you consider how the tuned pipes and electric motors work makes some sense.