I'm not one of the aerodynamic gurus here... but here's what I believe is happening.

With the F-16 using a super critical airfoil, two things happen:

1. At high speed, (and only at high speed) drag is reduced.

2. At low speed, it serves as a "lift dumper", allowing the plane to accelerate more readily on takeoff, and to "stick" to the ground on landing. (According to some F-16 pilots, this helps keep the plane from bouncing (ballooning ) if you're a little fast on approach. )

PS> I assume that at model size Reynolds numbers, you would skip the reflex, but keep the other configurations.