Breakdown of Healers across WotLK seasons

I'm new to WotLK, started doing competitive PvP in Cata. I looked through all the guides on the website and tried to search youtube, but couldn't find much discussion regarding healer viability across the seasons and how the landscape of healers changes as the game progresses. I understand in ICC gear that Paladins are incredibly good, and glancing at the ladder it looks like hpals and rshams have decent representation, disc priest is okay, but seeing very little resto druid, but that's about the extent of my knowledge.

Just looking for someone knowledgeable that has been playing Wrath for a long time to point me to a good resource or fill me in as to how each healer does throughout the expansion, and what type of comps they generally prefer in 2s and 3s. Any and all additional information such as counter comps, or reasons why they suck or are gods, etc. is much appreciated. I'm starting to play on Warmane as prep for the eventual WotLK Classic release in the future and am looking to learn.

Hpal:
+ Sacred
+ Buble
+ Extremly cheap heals
+ Beacon
+ Hands of...
+ Friendly dispel
+ High armor
+ Can help with dmg burst
+ Has high burst healing w/o too much setup
Good overall regardless of bracket.

Sham:
+ Little beacon via talents while using relatively cheap LHW
+ Bonus healing on targets with earth shield (-20% dmg taken)
+ Dispel poisons diseases and curses (if talented)
+ Purge, wind shear, hex, totems, hero/BL
+ Mobility with self heal (if glyphed)
+ Less armor than paly but still good
+ Seting up chain CC to force trinket/kill can be easier due to hex, windshear and grounding
- Less forgiving than hpal
Good overall, best in 3s.

Disci:
- Squishy before geting Bis
- Requires highest coordination with you teamates
- Buble (one of 2 strongest heals/absorbs) can be easily purged/dispeled. Penance is channeled so it is crutial to avoid kicks.
- Insta heals are not cheap while not so strong.
+ With Power Infusion can help in burst/go for kill phases.
+ Dispel, Mass Dispel
+ Fiend, Aoe fear
With the war/hpal smourne plague in 2s is proly hardest to play. RMP in 3s is a clasic. But without CC help from teamates is too squishy against more enemies.

Rdru:
+- Hot based healing that can be dispeled, but if not can help during CC
+ Mobility, Bear form
+ Bloom gives mana back especially when dispeled
+ Cyclone... Making enemy immune to incoming heals can make the game
- W/o applied hots burst healing is meh (purge spammers), can't use Swiftmend
- Can't dispel magic so when your rogue/lock is in poly you pilar hump like pilarsexual
- Certain bonuses to healing apply only in tree form which you not use in pvp as it can be banished and you need to help with CC (Cyclone/roots/hibernate)
- Requires high coordination with your teamate especially in 2s
Generally oriented to blanket raid/party in hots while leaving the heavy lifting of tanks to others. This translates somewhat into arenas as well so 5s are the bracket for restos.
After being the kings in TBC Blizz had to tone them down.