Because SMN relies so much on dots it might not be a good idea to just look at potency per second due to spell speed increasing both the cast speed and damage of dots.
i.e. Ruin = 80 Potency but Bio relative to Ruin could be a total of 270 Potency (completely dependant on Spell Speed value + Enhanced Pet)
My thoughts on an optimal opener
Shadow Flare placed
Minimum 2.3 GCD
B2MB -> Pain + Fester -> R2 -> Rouse/Spur -> R2 -> Enkindle + Radiant Shield -> R2 -> R2 -> Fester
R -> R -> R2 + RS -> Bio + Pot -> SC SF -> Trance + 3D -> R2 + Fester + Pain -> R3, R3, R3,R3, R2 + Fester + Death Flare