I don't think it was your fault this went downhill. Heavy, constant, tank healing is murder as Holy. What you could do to band aid it is to coordinate CDs with your tank. Use GS early, and fiend+ conc pot, then as the Shannox fight is long, you will be able to use HoH + fiend later again. Ask the shaman to use Mana Tide early as well, so it can be used again. Also make the tank aware when you need to regen and have him use a damage reduction CD so that he can live on very little healing. Perhaps you can use a lightwell near the tank to keep him up during low damage phases, i.e. when he has recently reset his Jagged Tear stacks.
Also, give your Disc a kicking. Tell him to get a Rapture counter, Shield every time rapture falls off, and inbetween chain cast Gheal and Penance on one target. That alone should have him do far more healing unless he is asleep. He only really needs three buttons for shannox (others are optional): they are PW:Shield, Gheal (macroed to Inner Focus) and Penance. Power Infusion, Pain Suppression and Barrier are optional. In fact, since you are having more issues and do more healing, one idea might be to ask him to cast PI on you.
Soooo... after doing all of these bosses on the PTR then raiding Firelands on live I surely missed my 3min awesomesauce Divine Hymn...
---------- Post added 2011-10-19 at 02:27 PM ----------
Oh and for the record it definitely scales with Haste still - on the dragon with 100% haste buff it hit 50 times for 1.32mil healing >_>
Pixl Returned! Holy Priest
yeah I tested out my holy spec as well on our last try and it came out at 54 ticks 15/54 crits, 2,435,113 healing done total not including mastery hots with a max crit of 72k (lightweave, power torrent, archangel)
and along with haste still working you can still use it on the tail end of any procs and have them count for the whole spell like usual.
edit: not sure why it was 54 ticks not 55 or 50 but it was oddly enough.
Agreed. Not to mention all of the other useful spells or abilities that they have that can save the day, such as a well-used Life Grip or Body and Soul bubble. The old Divine Hymn probably wouldn't have saved the day in most circumstances, but the new one is simply delicious.