Lynnea

Personally i run the 5 pieces and still wear the robe. Greater bane warding adds about average 10% to the tanks dps. There are a lot of variables, it goes off the tank's damage spell crit, so say if it was an sk tank it would probably do more.
Your stances, warding spirit and the other offensive stance (can't recall the name at the moment) also effect how much it does. as well as the casting expertise stacks with the offensive stance increasing the damage proc more. I love it and use it over most the other gear I have for now.

As for the breastplate proc I have it and tried it and really prefer the SoF robe. I personally like the reduced cast time over the small ward it does. Especially doing instances with less than ideal groups and solo healing.

As for raiding, I left it up to my MT and he likes the added dps since we don't have any troubles keeping him up. I carry my other gear, like the rune etched helm and various other raid gear, on me in case I need to swap out but have yet to need to do it.

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