The Swift has been spun unintentionally and the Millennium may do so as well. Both of these craft are somewhat swept and tapered with low twist. The Atos isn't too tapered but will spin like any sailplane if aggravated. When you are in a spin you are out of control and can go nowhere unless you stop the spin and resume normal flight. The main danger of spinning is, of course, hitting the ground.
Spins still account for a large percentage of fatal accidents in both sailplanes and airplanes.
It is important for those of us flying rigid wings to know enough about spins and spin recovery to prevent the same statistics in our sport. One of the most dramatic things that happens in a spin is disorientation or vertigo. When I first started doing spins on my Sensor years ago, I noted how quickly the effects of vertigo build up. The reason for this is that a spin tends to rotate you around more quickly than even a very tight 360. Dr. Fred De Lacerda writes a column in Sport Aerobatics magazine illuminating this and other subjects concerning human physiology in dynamic flight situations.