You use Scared Shield in PVE? Hows that working out? Never tried it
It's very strong. Overall with defensive CD's, I'll typically take less damage than any other raid member during those heavy raid damage moments. I'm a much bigger fan of preventive damage, rather than simply throwing a heal out. First off, Sacred Shield can be applied regularly in your rotation. While Eternal Flame, and Selfless Healer can't. Not very effectively in my opinion. So it allows for a near constant damage reduction. Then when you hit heavy raid damage, such as Rain of Blades, you're TAKING less damage. Allowing your healers to focus elsewhere. Because we all know they're going to try to heal you if you get semi-low, even if you have Selfless Healer ready for use.
In my opinion, Sacred Shield is a very important talent. Mainly because it's a filler for those gaps in your rotation. You're better off reducing your damage, than doing absolutely nothing for a GCD.