The issue with this Meta as Destro is that when u get @ 5k haste rating and have a backdraft ( most cases in destro spec ) and this meta pops , u getting below GCD incins
don't even think about under Hero / lust , which ends in a DPS loss in the end waiting GCD to catch up.
Tried on HC Horridon and was having my incinerate 0.96sec with only Backdraft.
As affliction i think benefits you more , haven't tried Demo cos i got this only today.