You're not alone. A warlock has actually been putting Dark Intent on me (I'm a healing priest) on five-mans, because she thought the healer to be the best choice. (No, I didn't ask for it.) Let me know if this isn't ideal and I'll let her know.

http://www.mmo-champion.com/threads/813759-Dark-Intent-The-Guide-%282010-12-24

I'm fine with sticking to healers, especially in Raid Finder or PUGs.

Cool. I'll just let my friend keep doing what she does, then. :"D

Philster043 the rule I have in my head (can't remember where it came from) is healers for progression, DPS for farming. On that score I generally hit my raid's restro druid with it, or the healing priest if the druid is tanking. We don't have any sprists or balance druids in raid, so I usually just leave it on the healers.

I'm a holy priest (main) as well, and I get DI a lot in dungeons, and I do think it's a good choice because of a holy priest's mastery in conjuction with Renew. And resto druids are a pretty obvious choice as well, their healing being comprised of mostly HoTs.

My holy paladin alt has actually gotten DI a surprising number of times in dungeons, which always surprises me, since the only HoT they have is Holy Radiance...

I think the main reason people put DI on a DPS over a healer is because it'll boost the DPS of the other person as well, but in a 5-man there just might not be any better choice.

If reforged right Holy Radiance is a great spell for Holy Pallys, and benefits well with DI.

In my 25 man runs, we have a HPally that's reforged everything to haste, and gets about seven ticks off HR, and with judgment gets the cast time down to 1 second. So he'll have HR ticking off seven people at the same time, causing him to have more crits than any of our other healers even have ticks of HoTs.

Healing priests are receiving the buff because many locks know about our PW: Serenity. Our 25% crit chance increase every 7 seconds is tasty to locks, especially in 5mans when it's crappy melee as the other options. I even give it to healing priests, and DI stays stacked on me for the entirety of the dungeon more or less.

(I have 2 mains, a lock and a healing priest, and on my priest I too get it in 5mans.)