I disagree with you, Peaches, that Adlo is useless in 8 man content because it's immediately eaten up.

Damage prevented is damage never taken.

That's damage that never ate into your tank's healthbar. That's damage that you don't have to heal up later.

Is it expensive? Yeah. Why is it expensive? Because half of the Adlo spell is a guaranteed fully-effective heal. That's also why Succor is expensive. Any time I heal as a WHM, part of my healing will almost certainly go to Overhealing. If I use Medica, that chance is greatly increased. If I use Medica II, it's basically guaranteed. But while the actual heal part of the spell may go to overhealing, the Adlo bubble itself never will. And that is why it's expensive. That's also why it's far more powerful than you realize.