http://www.worldoflogs.com/reports/r...?s=9833&e=9893
http://www.worldoflogs.com/reports/r...=10015&e=10078
These are the logs for the P2 portion of your kills. Your Holy Priest was actually using DHymn at the start of the phase before Shock Pulses come out.
Anyway, DHymn is undoubtedly nice for P2, but I would sooner take Disc's ability to constantly spot PW:S for the entirety of P2. Deaths aren't congregated, which dilutes the effectiveness of DHymn. Also, after looking at your logs, it looks like the majority of P2 deaths could have been avoided with a PW:S. Finally, Atonement/Penance offers more focused spot healing right after each Shock Pulse. These are all factors brought by Disc that go beyond numbers alone, and actually contribute towards the survivability of your raid.
The situation is completely different on Galakras though. Your logs show misplays by your fellow raiders that cause them to take fatal damage within 1 second. There's no way to triage that outside of ensuring that you have PW:S on everyone constantly, or reacting to that kind of damage with <1s. And hey, if you have such amazing reaction times, then kudos to you.