PS..yes, the airfoils I've drawn are symetric...(so I was already being unfaithful to the original).

With this design, I think Patrick was influenced by all the Mumbo-Jumbo about how flying wings need special airfoils to fly level with the least drag.

If delta models are kept light enough and sleek enough I've never noticed more than the slightest amount of "up trim" dialed into the ones I've flown .
Of course, finding the correct CG for the best dead stick glide needs to be established first before analyzing how much "reflex trim" is needed.