Andy, I can't speak to the SawStop, so don't know why one set of dados will work and another is incompatible. In general when thinking about stacked dados, they are all pretty much the same on the outside; i.e., two beveled toothed blades with the bevels on the waste side. The chippers and shims vary from brand to brand.
I bought the 8" Freud set largely because the chippers are each 4-toothed, not 2 as are many (most?) of the rest. The increased number of teeth and the increased mass of the unit combine to reduce vibration and give a smoother cut on both the bottom and sides of the dado. (For the same reason, this set might not be suitable for lighter, contractor saws whose arbor bearings might not like the extra load).
I agree with Dana that the smoother the cut, the better; less fighting with "schmutz" in the dado during assembly, or less cleanup with a router plane. The Freud set comes with a good set of metal shims; my only complaint is that the shims aren't etched with their thicknesses, but reaching for the calipers isn't vary strenuous.
