I personally don't like to makro things and it takes the individuality. Anyhow I understand your point and would probably do the same in your position. For everyone which is not RL I would go with another solution than makro on specific people. Nothing more disappointing than "this target is not alive" while u want to feed a group.
Btw. my personal target is not to keep everyone above a specific limit.. I just want to have everyone everytime mana they need it, if it means they finish with they're last spell and dead of the mob at 0%.. so be it.
I, more than most men, suck ass at multitasking.. I can manage just fine taking care of power raidwide, while dps-ing, potcuring and a spot arcane cure every once in a while.. But ever since I have been asked to lead raids my overall performance has gone down dramatically.
Enter -- Macro's
Also the most likely reason no-one will ever understand my UI
you're a halfing... it's ok