Sorry, can't agree,
Dutch Roll is a mode of motion rather than a stability and is a product of directional stability (the "spring") and roll damping (the "damper") where a sideslip excursion is countered by the directional stability and the ac overswings. Each sideslip excursion translates into a roll IF the ac has strong dihedral effect (eg Harrier 1 at approach speeds) if NOT then the ac will snake rather than roll-this is still Dutch Roll (eg Harrier 1 at 500 kts-DE being dependent on alpha among other things) The magnitude and frequency of the dutch roll motion depends on the directional stability and roll dampling. Dutch roll can be divergent, convergent or neutral. Dihedral Effect characterises it only. The best way to stop Dutch Roll is to kill the sideslip. Anhedral helps reduce to roll due to sideslip-a good this for xwind t/o and landing.
JF-Intresting comment-any more details?-is this simply a divergent spiral mode or something more complex?