All my kills have come in two sets, but I generally have done that in larger raid sizes (all the way up to 30) where I've found it's easier to meet DPS requirements. One of the advantages of large raids is that the DPS of the tanks is much less relevant, and 5-6 DPS can be added per healer once 2/4/14 is exceeded. Although that's thirty crescendos to dodge!

Tonight I was running a pug and the DPS was just at the level we needed to push P3 right on time but to do so both ranged adds were near 100% and it caused some pretty serious problems. That was partially due to DPS not switching, we had at least one pull where Denathrius was at 30% before the adds went down which is WAYYYY late IMO. It is a little tricky though because they can't really be DPSed during the first shatter nor the Hand that comes after it as the first soak is done, so if they're up, they're up for a while. Then the second shatter comes which is IMO the best time for heroism/bloodlust and if those adds are up it's damage off Denathrius. I've never tried hero in phase 2 although tonight it probably would have been reasonable, especially if it got us in to phase 3 clean.

Most my kills the DPS was absurdly qualified (like raid ilvl was north of 220) and we could kill three of the second wave and still push 40% easily. With DPS like that I think two-phasing is a no brainer. There's a lot of ways to die in P2 and the shorter it is the better.