If you want a near-estimation of shields, I guess it is not a very difficult task.
Basically, all you need is an estimation of the max-mana of the player. As this should be a constant (or close to a constant), a few heals - rapture matching should be enough to get a fair estimation (let's say within 10% error). One could even consider to ask the player to give this piece of information.

Then all what one has to do is to compute the mana returned by rapture, and the effective heal of direct healing that proc rapture (penance, greater heal and flash heal). The first one is very easy to compute, the second is already computed in most meters. A quick computation based on max-mana and direct heal gives you the rapture-return from direct heal, you substract it to get the rapture-return from shields, and you can get shoud shield absorbed amount.

Now, let's consider you have 10% error in your max-mana (let's say you over-estimate it).
This means that the rapture-return from direct heals will be over-estimated by a margin of 10%.
Considering that 30% of your total heal is shields, 50% rapture-concerned direct heals, and 20% other spells (binding, POM, POH, renew, glyphs), this means that 62.5% of your rapture-return is from direct heals (and 37,% from shields).

Rapture return from direct heals is 10% over-estimated. Therefore, you estimate only 31% of your rapture-return from shields, instead of 37%. This is a relative -18% value (you under-estimate your shield based rapture-return with 18% error). Now, over-estimating max-mana by 10% means again that for the same rapture-return, you underestimate the shielding by 10%. Basically, final estimation of effective shielding is 73% real effective shielding.
Back to 30% of healing done by shields, it's 5% error estimation in the total healing.
This seems to me an acceptable error compared to what we have (especially since we should be able to get less than 10% error on max-mana).

NB : Of course, this assume a perfect rapture in live. But I don't have any realistic value to estimate or correct the partial absorb bug.

With regards to updating my profile, everything that I am able to put into my profile, I have, so Im not sure what else you want me to update - sorry. With regard to the SOL and IHC procs, I didnt imply they were guaranteed at all, but generalising the increased chances on crit to proc SOL and IHC from COH, for the purpose of the OP reconsidering spec and healing execution for mana as deliberatly overhealing to obtain mana should never be pursued or recommended. Both SOL and IHC procs when I crit on COH, at least thats what Ive seen happen over and over again. Ive been watching them for absorption of FH and GH due to the question in a previous post about IHC being absorbed when SOL is absorbed. I do not at this time have WWS as since this guild that Im currently in does not use it, I disabled it. I will however download the client again and obtain that information for this purpose.

Which was the purpose of my respec into Meditation, Mental Strength, Mental Agility and Focussed Power, all of which increases my mana regen while casting (30%), intel (15%) , healing by another 4% (on top of what holy already provides) and decreases mana cost of instant casts by 10% (POM, COH, Renew). Along with that, regearing into higher int and crit. Perhaps you are running with a lesser number of healers than we do and you have much higher haste than I do? My haste is only 54, and we run with 7 healers. Also, what is your overhealing? My overhealing is usually 9% - 10% maximum. You have quoted my armory URL below which is correct, so you should be able to see my gear setup there. Is there another place in my profile that Im supposed to put that in because I cant see it on my Edit Profile page.

I have been gemming spell power, intel and crit and am now giving greater priority to haste. My raid buffed SP is 2722, *Edit in Naxx without spirit trinkets* my raid buffed SPI is 1302, and my raid buffed crit is approx 19.62% (24.62 Holy crit) from memory. My haste is very low yes, my first objective was to get my int and crit to acceptable levels as I was sitting on 6% crit 2 weeks ago and Im now sitting on 16.46% (21.46% Holy). I have not yet experienced haste as being a problem due to the high frequency of SOL and IHC crits Im getting throughout the fights, mainly from COH, although I am working on increasing it. I might just add into this aswell that Im not flasking or food buffing spirit, but instead SP, nor did i have to use inner focus, regen trinket or mana pots.

I will definitely be grabbing more haste gear, thankyou for that and I will definitely get the WWS parse for you to see this week after reset and refer back to this post to demonstrate. I can only add that I am in the top half of healing meters. I also do have the 4 set bonus for GH, and that since the patch, we took H OS with two drakes, I was alternating between MT healing with 2 other healers (GH only) and taking the portal to heal raid intermittently, so constantly healing. In Malygos, Im raid healing keeping HOT's on the tank, POM up, COH, renews before vortex, POM in the vortex, COH on landing followed by flash heals, and POH when necessary and using many SOL and IHC procs from COH on the raid as needed, as I said in my previous post, I use COH every time its off cd. Thus the reasons for sacrificing spirit in favour of intel, crit and now haste.

I also do have the [Majestic Dragon Figurine] and the [Spirit-World Glass] and have not needed to equip those either *Edit - have not needed them in Naxx - apologies - I do equip them in H OS and H MALY*. It may seem unbelievable, Im anxious now to obtain WWS for you so that it may be believed. If I'm wrong regarding both SOL and HC/IHC proccing from COH crits, then I must be blinking while unknowingly casting another direct FH or GH prior to casting COH to obtain the procs and I'll stand corrected. (Aware that the HC/IHC talent omits COH)

Ill get back to you on it with a WWS parse later this week.

Are you serious? Loatheb is a great argument for NOT getting SoL. You're missing a very important thing here, instead of the PoH > CoH > SoL FH you can instead use PoH > normal FH > CoH and the flash heal will have ~80% chance to crit, instead of 0% with SoL. And more importantly, SoL will lower your smite dps by quite a bit if you aren't running out of mana and you will spend the majority of the time nuking, not healing. Pointless discussion considering the difficulty of the encounter, but how people could consider a talent that causes your spells to be unable to crit in an enviorment with 80% chance to crit good bogles my mind.

There is no spell power cap. There is no hard cap, soft cap, or even a situation that might look like a cap. I have no idea where this idea starts, although I've run into it more than once.