Yes there is a lot of room for manufacturing error and the people manufacturing are not modelers. Shimming the front tail section mount up 1/64" on the wing changes the stab angle over 6 degrees. A wide range of stab angles might not effect the way it flies. But it seems logical based on other airplanes that the speed would be affected. On conventional airplanes as the aileron sweet spot is found the speed goes up significantly maybe 8 to 10%.

Bill