presence of mind needs a shorter cooldown or a longer duration.
full disclosure: i have, and play, both WHM and SCH. both are well geared (although the WHM has a TON of crit due to all the shared equipment with my SCH). SCH is my main. and lastly, i don't think PoM is useless in its current state, something i've heard from others. conversely, i think it's a great skill, and the spell speed is highly noticeable.
with that being said...10 second uptime? with a 300 second cooldown?! at least one of these needs to be changed. the values are confusing within the context of the recast times of other WHM cooldowns. benediction, with its minutes-long CD, is obviously supposed to be an emergency ability. likewise, divine seal, arguably being the much stronger skill, suggests that it should, or at least can, be used in the same fashion. (ie, as an oh-****, last resort ability). yet the low cooldown goes against this idea. meanwhile, PoM's lengthy cooldown, like benediction's, effectively forces you to save it for emergencies. but if this is an emergency ability, it certainly doesn't feel like one. again, the spell speed is nice. i'm not disputing that. but the fact that the spell ends just as quickly as it began, combined with the fact that DS more effectively functions as a last-resort-need-healing-right-now ability, and at a MUCH lower cooldown, makes me wonder what the purpose of this spell is.
note that i'm being at least partially rhetorical here. i don't mean to imply that i haven't found a use for PoM, because i've found many. i'm also aware that it works well in conjunction with divine seal. i just think that it provides too little for the cooldown, on which i think we can probably agree.