Personally, if they just the damage output to be like 5x then normal spells I would be fine with it. Overall though, I would have to agree with everyone else here. They were a sad thing to get when ya hit 44 and its damage was very similar to elemental II spells. Flare has always been my favorite spell from all Final Fantasy games and this was a to sad. I have also tested pretty much on all NM damage output of Profundity II+Blood Rite II+Dark Seal+any AM spell with battle regimen and being on the top setting for greatest output damage and at best it would hit maybe 400-500. Which normal spells like Fire II for me with Profundity would hit for 400 by itself. I really hope they change the setup or at least change damage output.

An interesting theory a LS member brought up that has worked sometimes but not others, is that when the ancient magic buff is up, any spell of that element you cast will boost the spells damage. So if you cast Flare, then Burn II, Fire, Fire II, cycle, it will actually enhance the damage of the Flare. It's seemed to work on some mobs but not others, so your testing would be great as well.~AngryNixon
I have tried this myself also, I really can not say it works, or it does not work. Like your LS member I was getting random numbers, and for spamming spells left and right it just does not seem worth it mp wise for the small damage increase if there is any. Though due to recent MP regen, you can just disengage in combat now and get mp back, so maybe it will be worth it for the time being till hopefully they change it.