While I detest intentional double merle breedings, that article is pretty inflammatory and misleading.
I don't even know why they brought sable merle into it for one thing. The merling in sable merls is
identical to the blue merle. The only difference is in blues the merle is overlayed on tricolor, and in sables it's overlayed on sable. IMO, keeping blue and sable lines separate is detrimental to the breed because you're still essentially breeding for color.
Crossing color lines does
not produce dead fetuses and blind deaf puppies.
From a color standpoint, all sable merle means is that you can get more
colors per litter (merle notwithstanding), vs. one or two.