small healing spec question

[cyonaris]

hey guys its cyo. I already have a spec picked out for tbc once at lvl 70. I just want to hear the opinions of people as to whether i should add into reflective shield which reflects 50% of dmg with 5 points into the talent, or put 5 points into mental agility which lowers the mana use of instant cast spells by 10%. would like to hear peoples thoughts. Keep in mind this is what i would use for instances/raiding.

thank you