If you're going 15 points into it you should probably put 20 instead due to the 10% armor increase.

I specced that way in the begining since I had the same problem. Getting from 1-70 pretty quick made me lack good gear but as the time passed and I got better gear I don't have that problem anymore, I rarely get focused and I can take pretty much heat with ES up.

I did actually try that for my very first day of 5v5 Arena matches. I started when my 5v5 team had a 1300ish rating.

I initially had the same idea as you-- I assumed I'd be taking heavy focus fire and picked up 5% dodge, 5% block and Toughness. It worked decently well when I took focus fire, but a stun completely negates the dodge and block. And, as far as I know, you can't block, dodge, or parry while casting. I don't know about you, but I tend to spam myself with heals when I'm being focused.

Fast forward a few weeks: Our rating is in the low 1900s and we're playing against some seriously smart teams. I rarely, if ever, get focused first; control, focused burst, and sapping healer mana is the name of the game. I took those 19 points from Enhancement and placed them into Elemental, picking up Concussion, Elemental Warding (really love this), Elemental Focus, Reverberation (love this), and Eye of the Storm (love this too!). With the +5 yard shock bonus of the Gladiator Gloves, I can take a more offensive approach to shocks which, with Reverberation and the Gladiator Gloves, offers so much utility that I quickly forgot about my 0/19/42 spec.

I'm probably too hesitant to sacrifice my healing/mp5 and really take the plunge and load up on PvP gear, though I feel that I have an acceptable level of survivability.

I use the Gladiator BP/Helm, Seal of the Exorcist, Timelapse Shard, and otherwise pretty much my full PvE healing set (as seen in my Armory profile). I end up with 120ish Resil, and over 10k hp with buffs from my team. My high armor (Mag shield, all epics with high base armor values, etc.) makes me reasonably durable against melee focusing, and Elemental Warding helps with most casters. When I first started out I definitely had survivability issues, but since I finished getting the above pieces together, it's been a while since I can say we've probably lost a match because I died sooner than I should have.

The tradeoff is that I can PvP with 1300ish +heal and ~110 mp5, and the longevity is tremendously helpful.

I don't think it's valid to use buffed HP when you argue 5v5 survivability anymore, if a team is going to focus you down they're going to purge train you unless they have a very unconventional setup that doesn't include priest or shaman. Unless you're getting killed in the first 3 seconds with a triple pyroblast, buffed hp probably isn't the number you should be using to determine survivability.

Certain classes are good targets just from the fact that a good portion of their survivability comes from dispellable buffs.

I think this question got edited in late and perhaps overlooked, but I figured I'd bump it up to see what other's thoughts are.

At first glance it seems like a worthy upgrade, I'm using TotPlains right now, but after I finish buying the armor set I'd considered buying this. It seems like a win, I use LHW a lot (perhaps too much, but I'm over-paranoid of getting interrupted), and the trade of +33 on LHWs to +26 resilience seems useful, and getting another magic effect up on the target to soak dispels is an extra benefit.