Priest tier 10 set bonuses, good or bad?

I was extremely lucky on my very first Toravon 25man kill. Toravon is the new boss in VoA, and like the other bosses fairly easy. We pulled a group together and killed him and two priest tier 10 gloves dropped, one for pve and one for pvp. We were two priests in the raid, one who mostly raids (me) and one who mostly pvps so we quickly decided to take one piece each.

My old gloves were definitely less good being of ilvl232. But, they were part of my 2set t9 which I'd have had a hard time breaking, since the set bonus is so god damn good. It makes Prayer of Mending heals for 20% more. PoM is easily one fourth of my total healing done for nearly any raid encounter, so that was really a good setbonus. But now that I got some better gloves I started looking at the bonus of the new tier. Would it be able to top 2 set t9? Would it at least be good enough to make the upgrade about equal?

The 2set t10 says "gives your Flash Heal a 33% chance to cause the target to heal for 33% of the healed amount over 9 sec".

First of all... Flash Heal? Sure, it's an important skill. But not that important. I actually use it less and less the more I get into ICC. I definitely use it less than PoM! But still, I do use it so this doesn't have to be a bad thing. Putting focus on it in a set bonus might make me want to use Flash Heal more than it's good for though, which was annoyed me. It depends some on my spec though, since when being holy I mostly use spells like PoM, renew and CoS while in disc I use Flash Heal more.

Second of all... 33% of 33%? That's not many % in the end. PoM was 20% straight of off a spell that could total heal 50k with lucky crits. But 33% of 33% is (and correct me if I'm wrong, I suck at maths) about 11% of a total Flash Heal. 11% of a spell I use less often or 20% of a spell I use mostly? Right there it didn't look like an upgrade at all.

But, I have to try it out before I diss it. My first "trial" was simply spamming myself with Flash Heals to see how often it would proc. I know from first hand experience that 33% doesn't have to be anything like 33% if Blizzard's in charge of the programming. While spamming myself I noticed the proc rate seemed about right, but I also noticed something else, potentially awesome. Blessed Healing ( as the proc is called) actually stacks! Yes you read right. If I've already got a Blessed Healing buff up and another one procs, it not only refreshes the duration but it also adds the new heal to the old one. I managed to get a Blessed Heal hot up and ticking for around 7k every two seconds before I had an unlucky streak where it didn't proc and it dropped of. 7k hot tics... now that's alot. I immediately saw what benefits this little set bonus could have.

Now I don't know if the new proc also refreshes the old procs total healing, or just adds to what's left of it. If it would refresh the old one... well that would be awesome. And I actually think it does. I'll have to collect more data on that one though.

My second trial was doing some heroics, and aiming to cast as many flash heals as possible, to see how much of my total Flash Heals would be Blessed Healing. My first try, a CoS run, was a great disappointment. I had FH'd for 282k, but BH only healed for 12k. 12k! I thought this could have to do with most of it being overheal, and maybe it doesn't register pure overheal ticks, I'm not sure (I use recount). My second run was HoS and I FH'd for 278k and BH had healed for 25k. Slightly better but still really low.

My last trial will be in a raid setting of course. I haven't had the opportunity to try that out yet, but will tell you about it as soon as possible. The ICC raids however either have alot of aoe dmg (Blood Queen, Putricide, Festergut) or alot of point dmg (Blood Princes, Saurfang, Rotface) so I think the best solution will be to use 2set t9 for the aoe fights and 2set t10 for the point dmg fights.

Pros
- Stacks giving potentially awesome hot ticks

Cons
- Based on a less frequently used spell (depending on spec)
- Goes against the way a holy priest heals, making it better for disc