I'm a paper priest, sure. But as a ligth armor wearer you are a paper priest too
Wearing Very Light armor give you less mititgation, right, but Mitigation at Ligth or very light is important only when solo.
If you are in a group killing heroics if you gain too much agroo you'll die with cloth or with leather. That's a fact and I saw this many many times 
I saw a plate wearer being killed with ease (a Inquisitor)
The only ones ready to recive damage are the tanks 
Our Mitigations Sucks... is a fact. So try to keep a good power pool and a good Int value. That will make you a valuable healer (And don't forget to keep upgraded at max you heals and buff 
)