I play in a 10man raid, of whom is currently working through Amber Shaper. Everything prior to this is on farm, and pretty much everything can be 2-healed by us other than maybe Heroic Stone Gaurd (we're 1/16HM) and Wind Lord. Amber Shaper, we're already leaning towards 2-healing, since our bigger problem seems to be with bursting out teammates our of constructs without drinking pools.
Being a druid who can play both resto and boom, I'm the one that flops between DPS and Heals. To date, I've primarily been gemming and enchanting for resto. When it comes to going DPS, other than swapping on a few boomkin-specific pieces, I just reforge before the pull.
Being gemmed inefficiently aside, the additional of the valor upgrade gear will exacerbate the problem some more. Now, to be clear - the inefficiency is significant but not devastating, and I'm not complaining. This is merely an intro.
TLDR; I play resto primarily, then play boomkin on 2-heal fights. Farm content can be 2 healed, and many progression bosses seem to benefit from 2-healing. No content thus far seems as though it requires 3 optimized healers, but can survive with 2 optimized healers and 1 slightly unoptimized healer.
My question is, how are you 3rd wheel healers (so to speak) going about this? I'm half-way considering I should be gemming/upgrading for boomkin, leaving my resto set less efficiently tailored. I'm curious whether I'm the only one who feels this way, or if you think I'm nuts.
Our "3rd wheel," as you put it, is gearing his dps spec atm so that he can actually do competetive dps (lol at about 30k less than everyone else), keeping his healing set for the fights where we do actually need 3 healers. In general I'd say gear / gem / enchant for the spec you use the most.
This is actually one thing that 10mans have a huge disadvantage of. Depending on what your other two healers are you should probably get one of them also to start to build a DPS spec.
As for what to gem/enchant it's always for resto. If need be they can summon you back and you can reforge for dps if it's really needed. However it sounds like you're doing mostly normal modes and there really is only a few fights that NEED to be two healed. The rest can be 3 healed with ease, so don't worry about it. Just keep trying to pick up Leather gear even if you already have the same piece. That way you can reforge/gem/enchant that one to max boomkin.
As for 2 healing Ambershaper, I wouldn't even bother. You're going to find that in p2 and p3 you can get really screwed over if a healer gets picked. If you're not able to get people out that means people aren't dps'ing them down. The best thing to do is look at when people die and look at who is doing the most dmg to who and call the low ones out. Chances are they feel that they don't have to dps the person down and don't.
Through out DS I was the third healer that would have to switch between Disc and Shadow thus leading to me being shadow full time as everything became two healable. In current content we have our shaman switch between heals and dps (enhancment) you might want to consider building a feral set as you won't need to bother about reforging or regemming. For Ambershaper and Wind Lord we two heal and have it on farm and most parses seem to be going 2 heals.
As a raid leader, one of my peeves for T14 is the number of the fights that are best tackled with 2 healers. I've got too many healers in my team because I was expecting to need 3 for most fights, but so far we're using 2 for everything. I wish every damned fight would require 2 tanks and 3 healers; if we want variety in who's doing what, we can manage that ourselves, don't force it upon us.
I am in the exact same situation though I opted to move to DPS on 2 heal fights because my resto set worked at the time and neither of the two healers had DPS specs.
The way I look at it is like this, your current gear is sufficient for you to heal the fights you need. Changing gems/reforges/etc will not hurt you enough to make these fights unhealable for you. However, changing your gems/reforges WILL improve your DPS by a bit. Also, you will quickly get near gear that you can use to make two sets. So unfortunately I lost some spirit (down to 7k) and am over on the haste cap (3500) but I can still heal all the fights I need to heal just fine. You will primarily be doing DPS so you should reforge/gem/enchant for DPS. You won't hurt yourself enough that the fights you currently 3 heal will no longer be possible with this slight change. So you may as well maximize the role you will be doing most.
we're 2 bosses behind you, only 6/6 3/6, no heroics yet.
i actually have almost 2 complete, separate sets. the only shared items are my rings and my staff. my boomkin set is about 2-3 ilevels behind my resto set.
but, i've been thinking the same thing. it seems that whenever we 3 heal (and i heal), healing is never the problem. none of the healers are stuggling for mana, and wipes are rarely because of lack of healing throughput. in fact i always run with heart of the wild and int flasks/food so i can add as much dps as possible.
the shared items are actually reforged for boomkin though, and i don't bother to change them. and both tier pieces i've gotten i used on boomkin.
i am definitely feeling like it would be better to prioritise my dps gear over my healing gear.