Post by sugarzombie
i spec'ed similar so my raid could have imp DS, but i wanted CoH. Mental Strength and Mental Agility are great to have because as 1 of 5-6 healers in naxx25, i spend most of my time keeping renews on tanks, mending as often as possible, and CoH when raid needs heals. Flash and Greater heal are mostly overheals.
a few points of improvement to OP's spec:
Move 2 pts from Imp Holy Concentration to Serendipity
move 1 pt from Surge of Light to Healing Prayers (since mending is the #2 healing spell)
move 1 pt from Emp Healing to Healing Prayers (you will mend more than you will gheal or fheal)
if you are just backup healing, consider taking the last 4 pts out of Emp Healing for Imp DS (to buff caster raid dmg a little) and Focused Power (which will apply to CoH / Prom / Renew).
so after all that: http://www.wowhead.com/?talent=bVcbkhxtrZcxtccMqVu0ho
i've used this spec in naxx25. the only time my healing looked week was on Patchwerk, where i am inevitably the lowest. your single-target heals are weaker, but you have great longevity and give nice raid buff.