So this place has turned into a serious joke. Thanks Nivek.
To the OP...if you still give a shit. I ride the Force on my rail board and the SL on my all mtn board.
The SL baseplate is stiffer and more responsive than the force.
The SL Highback has more torsional flex then the force but the same lateral stiffness. Dampening is the same...which is decent, but obviously not like riding on pillows.
The SL has a slightly softer asym ankle straps, the force have a stiffer uniform strap.