In general... the factory cant afford to put the kind of higher quality parts into their skids as the aftermarket can....
For example... the K-mod has low friction bushings on all of the pivot shafts....compared to the stocker that has metal on metal for the pivot shafts.
The shocks are a much higher quality package than stock... valving packages tailored to the rider and better components internally...even the oil is better than the stockers.
A coupled suspension has a different feel than the stocker.
The coupled design will keep the track in the snow when you are climbing... keeps the track more parallel to the surface than the stocker and not digging a trench to china.
If you've got the cash, this will definitely be an upgrade to your sled. The adjustability factor with the shocks and coupler adjustments will add dimensionality to how your sled rides.
Kevin, the owner of KMod is passionate about sledding and offers great customer support when you need it.