So I have been using this DPS trinket on atleast one of my healing toons for a while now. It probably isn't going to make or break your raid but I find it fascinating that it works so well for a healer. Like the trinket says, you receive 383 intellect and 39 mastery stacking up to 10 times for each DOT you cast. While using this on my resto druid, I found that applying only one Insect Swarm on a target causes this trinket to give ten stacks of mastery if other people are casting DOTs on that target. So essentially this trinket is worth 383 intellect and 390 mastery which is great for a resto druid and only at the cost of one insect swarm. The buff doesn't fall off either as long as people continue to DOT your target.
Again, I just thought this was an interesting use of the trinket and thought I would share it. I've been using this since firelands was current and although it is a bit outdated it still may be useful for some people.