I'm not just a Master FP healer. I'm also a Warzone (WZ)
As dramatic and gut-wrenching as my stories thusfar may be, let me assure you: the latter is more dramatic and gut-wrenching than the former. It is only in the warzone that the healer truly comprehends the full gravity of his chosen role.
(Or "her". I generally use the masculine pronoun for brevity and to avoid such silly constructions as "him/her" or "himr". My comments about "healers" apply equally to a lady healer).
No Heroic, no Flashpoint -- Veteran or Master -- no Operation ... no combat situation outside the Warzone can come close to the horrors the healer will witness and personally experience there. Being a WZ healer tests your patience, perseverence and the thickness of your skin like no other activity in all of SWTOR. It's usually quite unpleasant.
Then why do it?
I can only speak for myself. I do it because there is nothing else for me. No other role is conscionable.
The Healer is the heart of PvP. Everything turns on him. Other roles are mere auxiliaries.
Don't expect a Tank or DPSer to agree. But then, that's why they're auxiliaries.
A WZ team is successful if ... it works best as a team. (Duh). But it begins with understanding roles in the WZ.
And those roles, reduced to the fewest words possible, are:
HEALERS: heal your team.
TANKS: protect your healers.
DPS: nuke the enemy healers.
If your WZ team doesn't understand those basic truths, then it matters not if you're perfect in every other facet of teamwork -- you will fail in the Warzone.
With the above as a starting point, you're ready to hear some WZ stories...