Like having a pet with 5x MP recovery, that does not help much unless you stop casting for a minute and go to sleep (which also increases mana recovery), which is annoying if you do all the time while you are in the middle of something. Map changes are not that common enough to warrant the use of this spell by itself.
Even though by the time you reach TM 40 you are probably ready to go to second job you will need it if you want to get the Growth Badge yourself while in first job - that alone would make it better than Aura.
Arrow followed by Ring provide similar casting speed as two Rings in a row. After that you need to run father in any case (so you can cast again without being attacked) so decreased speed from Ring is not that needed (unless you like pulling 3+ Rings in a row).
In any case, skipping Invincible Casting is really a no-no unless you like the challenge, and you will probably regret skipping it + Arrow + a mastered Mist (rather than one at lv 3) by the time you reach TM 40 at Caballa, especially considering Aura would have become almost useless by then and even worse after (as the MP recovery is fixed in absolute numbers, not by % of your total MP or your level).
In a few words, Aura can be useful indeed for those in 1st job, though changing priorities later on make it hard to justify a spot that early, especially if you are a hybrid.
Recette - Witch 400 | EmiriTachibana - Diva 400 | SakuraHiiragi - Champion 35x | AnaJessicaAyano - Soul Master 26x | LeslieSun - Witch 26x
Bye Bright Shadow Japan, I will miss you all and my bunch of characters very much ~~