Matt's original Arrow plan as well as the MK kit both had adjustable incidence stabs (the MK with its mechanism). However, they weren't full flying stabs proper. The mechanism for incidence adjustment doesn't have to be that different from that of a flying stab. MK and Gator both made incidence mechanisms while Geizendanner and Leo's "Flying Fork" are a flying stab mechanism.
David
I build a MK Arrow many years ago ...this had not adjustable og flyning stab..it was glued...a buddy off me also build several off them ...those was also the same..maybe difrence in what was shipped to europe and the states?