Like I said in my first post, I'm not trying to start a huge debate, just personal preference based on experience.
Foam flys better because the airfoil retains its shape. Look at your photo, especially the airfoil. Does that look very efficient?
Do you think that stays like that at 100 MPH?

For covering I use laminating film, $33 for a 1000 ft by 18" wide.

Sorry if I offended you.