We have a Holy Pally and plenty of shadow/disc priests that wanna dps/os heal but i wanted a ele/resto shammy for BL and a disc priest.... any advice? should i just let them dps/os heal with a shammy ms heal or hold out for a new priest and ele shammy? Im lost on what to do here.
Holy pallies are great tank healers. No doubt there, and disc priests tend to lean towards that role more, but in 10 mans disc is more than capable of holding their own as a raid healer if the need arises.
The first wing is do-able with 2 good healers. If you're trying to do this as a guild, and you're trying to gear people up, you may want to look at your raid balance and gear people up accordingly, asking a priest to go holy would solve your raid healing problems, but you still should look for getting 3 healers total for your raid (perhaps one that has an offspec dps that could do a bit of dmg for that first wing).
After the first wing you'll DEFINATELY want 3 healers. You'll want it. Ideally, you will probably be looking at 1 tank healer and 2 raid healers, thats not saying the raid healers ONLY heal the tanks, each fight is different and they should adjust accordingly, but there really isn't much information provided here, so I'm not sure what you're dealing with...
We two-heal with a tree and disc priest (me) through the first six bosses (first four plus Rotface and Festergut), and have no trouble healing Putricide up to our wipe point in phase 3 (that's another story). We have a moonkin with a good resto offset that we will probably use once we have plague down, however. We haven't had a problem with enrage timers yet (especially with the 10% bonus) and it makes learning the fights a bit easier when the rest of the group can afford to make some mistakes.
The first four bosses should be trivial with two healers and the buff.
I would guess in your situation it would depend on which of the off spec healers are good at healing and would be willing to make it their main spec for the last few bosses, if you try to force someone into using their off spec you may end up with halfassed results so either find one that wants to heal or get a replacement.
Being a disc priest I will suggest getting one of them since we are an awesome class
Dependent on how much experience your guild has and item quality the number of healers needed goes down almost to the point healers are doing pew pew in between the odd heal, at the moment with our strongest players and an average gear score of around 5800 ish we can down the first 8 bosses with a Disc priest + Resto druid, blood queen requires not a single person dies so we 3 healer for safety, I single heal the raid on dream walker with normally the druid and our off spec resto shamy on dreamwalker full time, Sindra and the lich king at the moment for us requires 3 healers though we only downed the lich king once with Hpally + Disc priest + Resto druid it was also the first time we used a holy pally in the same raid as myself a disc priest. If we had more main tank healers then just the two of us I would consider me and him two healing the entire instance but since we run two groups it is impossible.
The first 7 can be 2healed (Although its best to have a tank or DPS dispel at rotface)
As for PP damage, there isn't really much at p3 if people avoid goo because he will die very quickly, and it can easily be kept up by 2 healers.
for Blood Prince i guess that if you do it with 2 tanks (no ranged) and have 1 holy pala heal both tanks while the other healer aoe heal and shield/hot the tanks, the damage in there is not to big if you can control it.
As for Blood Queen, you can do it with 2 healers, however I have always done it with 3 healers.
For Valithria you can 2heal it if you have a very good holy paladin spam heal valithria.
For Sindragosa it can be done with 2, but not recommended as RNG will kill you if a healer gets iceblocked and the other unchained magic, effectively killing you.
For Lich King, I wouldn't recommend 2 healers, p1 and 2 can be done by 2 healers only, but phase 3 gets tricky, if one of the healers gets sucked into frostmourne, then 1 healer will be left out healing the raid.