in my opinion its a balance between int and spell power....over 26k approx mana and you get great mana returns..fully raid buffed i can break 34k so im starting to gem spell power over int'..i think if you have 27k unbuffed then start looking at sp over int. after that look for crit then haste and take mp5 over spirit.
you get spirit forced on you alot as thats just the nature of the beast quite often but its useless, all your mana returns work off your mana pool..ie: the more mana you have the more a fully absorbed shield returns and so on. i take crit over haste as most of my spells are instant..shield/PoM/suppression/nova on occasion..and my to timed spells are fast as it is..flash/penance..and you get haste after a shield anyway.
crit just procs more Divine Aegis so thats a win
and then find your balance of int and sp that you are comfortable with
int/sp..crit/haste/mp5/spi.
edit: spi doesnt give spell power or anything as disc either as we cant afford the points to allocate to it
it isnt always about tank heal tho if you can predict raid wide damage or if someones going to take a huge chunk of damage like marrowgar's bone spike toss a bub' on them..its mana returns for you,less panick for everyone else and the druid can complain about his 50% overheal =D
good hunting
