One thing to consider, is that using Energy Drain twice will give you the mana to summon the pet, but you get three stacks of aetherflow.

Also, if you sacrifice, er, dissipate the fairy while whispering dawn is running, you wont really miss her heals as much. You'll still get 21s of regen, so there is really only 9 or 10 seconds without support from the pet.

With Fey Illumination, then whispering dawn, then dissipate, Adlo is far more potent. I've had well over 5k crits with it (which is a 10k galvanize).

In Alexander, since accuracy requirements are so low, you wont miss with energy drain, so its a fairly safe bet to eat the fairy and burn a few energy drains to get a net gain of mana out of it. However in Ravana, (and even some of the L60 dungeons), accuracy is a concern, as Energy Drain can miss.