Well after running Pater's sim for a while it pretty much confirms what we postulated before in that Potency == Fiery for DPS.
Average over five runs Potency added 9.4 DPS (simulated by adding 40 AP)
Fiery averaged out to 9.52 DPS.
I simulated fiery by calculating proc chance (27% for a 2.7 speed weapon like Planar Edge)
then obtaining number of procs from total MH attacks
Fiery MH = 264552 Attacks @ 27% proc chance
[top] 71429 Fiery Attacks @ 48 avg dmg per for 3,428,592 dmg
9.52 DPS increase
Fiery average damage assumes
* +10% Coe
* +15% Imp Scorch
* +5% Misery
* 1.025 Crit modifier (5% for +50% dmg)
* 0.87 Resist rate modifier assuming Natures Guidance.
So Technically i would say that Potency is better as it doesn't rely on outside variables in order to perform. And of course either are stripped by Crusader or Mongoose.