I now have Astro, White Mage and Scholar to 60. As much as I was so pumped for AST, after playing WHM and SCH at 60 in the new dungeons, I can tell you how far AST falls short. It's actually really disappointing considering I really wanted to make AST my main healer. But, in the end, that is not going to happen.
With WHM and SCH, I feel that they are so on point that I can really add some good DPS to dungeons and while doing a great healing job, all the while never going OOM. However, on AST, you pretty much just heal or throw a card out most of the time, as their MP pool coupled with their lower potency doesn't give a lot of wiggle room to add in a lot of DPS. Their spell effects are gorgeous and I love the idea of Astrologian and their weapon, but in the end, they need some major love from the devs.