Ok. Here's some random retarded math:
~9 min fight (I had to stop because of a lag spikes). The old "RoF on CD" rotation. Incinerate spam, just few Felflames. And here I'm trying my best to use set bonus procs for bolts and immolates, Black Blood trinket proc, line up Purifide Bindings with dark soul and trying to save few embers for dark soul.
47 Chaos Bolts
479 RoF ticks = 60 RoF casts
According to what Zumzumzum said, 479 RoF ticks = 119,75 ember bits = 12 embers = 12 Chaos Bolts
RoF has the same cast time as Felflame.
If I throw out RoF and cast FF intead of it I'd get (60 casts) x (1emberbit per cast) x (1+ crit chance) ember bits.
Let's say I have 20% crit. That would be 60*1,2=72 bits = 7 Chaos Bolts
As you can see, in a 10 minute fight RoF gave me 12-7=5 additional Chaos Bolts. It wold be 3 Chaos Bolts for 5 min fight. (And a lot of unbuffed Chaos Bolts.)
And I can say that it was 10 minutes of HELL. Always low on mana AND embers trying to squezze some dps out of procs. (Same dps as brainless FF spam, by the way)
I don't want to write the rest of my math because it's too obscure and probably wrong.