I just sent my followers out on the Murder Most Fowl mission, successful completion of which awards Grandiose Trinket.
To anyone else who comes across this mission, please be aware that if loot preference is set to discipline or holy, you'll get Grandiose Prescience, whereas if it is to shadow you'll get Grandiose Power.
Personally, I plan on taking it as an int/crit trinket. I already have spirit on neck, cloak, both rings, and both trinkets, and the only time mana is really ever an issue is when things have gone so far south (basically bad pugs) that the lost amount of regen's likelihood of leading to a wipe is far less likely than the opportunities for greater throughput to prevent one.
Of course, this also assumes that my projected 96% success rate doesn't come back to bite me...