Healer since launch, never asked or wanted the guard. I cry when they put it on me in the few Operation fights where it makes sense to guard the healer.
2. When the healer is so overgeared compared to the rest of the group that he/she is able to keep the group healed and is doing more DPS than the DPS. This usually happens when leveling up but does on occasion happen in HM FPs..
Still don't want or need the guard.