I too have a Rallye with the Magic slats, and I can let you in on how they work: LOMCEVAK had it spot on, it's just migration of the stagnation point.
Most of you will know this,so forgive me for prattling on for a moment, but it might be new for one or two. The stagnation point is the point on a wing (section) leading edge, that marks the divide between air going over the wing, and air going under the wing. You'd expect the stagnation point to be pretty much at the front of the leading edge,but actually it's quite a bit underneath because of the upwash which goes on before the air hits the wing.
The stagnation point naturally migrates even further underneath the wing as angle of attack increases, and when it goes below the back lower edge of the slat, hey presto: out they pop! On the Rallye, you'll then immediately notice the heavy nose-down trim will disappear, along with the ugly tailplane buffet, and the craft will then zoom into the sky as smooth as silk. For a short period. Until all remaining kinetic energy has been translated to potential.
On the Rally, asymmetric deployment is avoided by interconnecting with control cables. No springs needed, just the aforementioned air dampers to stop them banging in and out.
Kolibear: Here's a useful flight test you can do. I won't bias your mind by telling you my results. Try a *slow* deceleration and see what speed the slats start extending, and finish extending. Then accelerate and see the speeds for the start and end of the closing course. Do this half a dozen times to make sure your data is good, and then repeat for a couple of weights. THEN, compare the figures to those in the flight manual. You'll find they're different, and I bet you'll find that the hysteresis in the manual (difference in opening and closing speeds to avoid them banging in and out in turbulence) doesn't exist. At least it doesn't on my French aircraft! I'd like to see if the PZL manuals are different.
Martin