I present my Epoch levelling spec, 5 points in shadow first, then disc then the rest in holy for optimal dungeon healing and PvP pocketing.
I rarely see Lightwell used and Guardian Spirit is a nice thing but 90% of the time I feel like it's a wipe anyway and you just get to watch for 15 seconds.

I would really really like to do a healing discipline build because PI, PS and PW:Barrier are a lot more interesting to me but I don't really know how attractive that is in raids, sounds like a 'There's one of these specs per raid sometimes' builds, so probably an OS rather than my main healing spec?