Potency amounts aside, I know and see what the damage difference is between casting a Fire 1 and Fire 4. An Average fire 4 at i180 is doing about 2100. A Fire 4 is averaging 3500. That's a 40% or 1400 damage PER SPELL difference, multiply times 4 for a typical full Fire 4 rotation, and that's 5600 damage lost over about 12-15 seconds. This equates to about 370 DPS lost each time you can't/aren't able to use Enochian and Fire 4 and just spam Fire 1. Maybe it's not an overall 40% drop in total DPS, but it is very close to that every time you can't keep Enochian going.