Thanks, Kithas—I think you're spot on about the 1st part (I had downplayed this aspect because... brain fart). The 2nd part is ok too, though only 1 target, which brings me to Chain Lightning.
At L6, SS becomes 4d6 AoE + 6d6 Lightning to 1 target, which is 10d6 (so, about same as CL for that...