(I think the people that still cry about helices are still in the mindset that they cost like 300 MP to cast. They don't.)
Well, look at it this way:
78 MP, and assuming 110 damage initial (a good high-end estimate from what we've seen so far) you're looking at 100 damage/tick. With ticks every 10 seconds, this is
roughly 33 damage/tick under the standard 3sec/tick system...but only on "old" targets.
With the "modern" stuff taking halved magic damage, you'll only be dealing 50-60 initial DoT at most, meaning only ~15-20 damage per tick--as much damage as a BLU could pump out with Cold Wave, for twice as much MP, no AGI down, etc. For spells that were hyped by SE as "massive DoT spells", yes it's more than Poison, Bio, or Elemental DoT's, but it's less damage than a jack-of-all-trades job like BLU can put out 10 levels earlier--and it still doesn't help SCH's lackluster offensive abilities for endgame either.