That was a well thought out post. To answer your very last question first, I drop both points from Haunting Presence. This lets me take Sith Purity, and place a point in Life Surge. I would recommend you do this as you get a lot of bang for each of those points spent in this way. You can afford to do this because Haunting Presence's 2% healing over an entire game is measly. Do the math and see for yourself. That is the best way to test things.
You should be using Purge basically on cooldown. You said you found yourself barely using it. Whenever you or a team mate is being targeted undoubtedly there are things you can Purge off yourself or others. So do this a lot.
As far as not going 31 pts into Corruption goes, Revivification is extremely situational and takes time to cast. It is sort of a no-brainer at this point. You take the last 6-7 points in the Corruption tree and instead place them into the Lightning tree (with all your other points) where you gain the best survival tools available, period. I won't bother to list all of the talents and how great they are. Surely you can handle that but if you need clarification just ask.
Also it does not make sense to put points into the madness tree as you just gain more dps.
Ahh now we're getting to it. That's exactly the feedback I was after. Thanks.
Your point on Haunting Presence is excellent, and I'm sure I'll work that into my template. Now you mention it, I'm trying to work out why the hell I had reservations about losing such a small healing bonus, for 2 whole skill points. Crazy.
On to your Purge on CD point, timewise I just think there's better things to use my GCD on. DoTs are so ineffective nowadays, that I feel it's easier to out-heal them, than cleanse them. I can either pull a 5k heal taking 2.5 secs, or a cleanse that will waste a GCD and stop a DoT that will probably only do about 2-4k damage over an awfully long time. Another over-simplification I know as sometimes there are multiple DoTs, but still I think the point is mostly valid. The effort it takes to monitor those around you and the DoTs on them just led me to a place where I would only bother cleansing myself and my tank. I've only really cleansed DoTs to get rid of movement impairing effects; something I certainly need to improve on.
Lastly onto your hybrid built. Building further into lightning to gain utility, rather than the dmg of the madness hybrid that another has posted on this page, is certainly the way I would go if I did decide to hybrid. The PvP role I play, as I explained above, is more about filling a support role, but that must include supporting objective play as well as healing your team mates. The utility those points in Lightning give are incredible and would certainly hugely help in supporting objective play... but I still don't think it worth ditching revivification for.
You describe revivification as extremely situational, which it is, but I think a good healer can overcome that. Revivification offers a stabilising heal, that you can then build upon with the rest of your arsenal. Its best attribute is that it helps keeps the peripheral members of your team alive, whilst you triage heal yourself, your tank and the other healer. With revivification, I would just have to let them die unaided.
If I might simplify just once more, it's basically revivification vs electric bindings, and I would personally prefer the AOE heal.