A classic example of overpowering through mechanics due to grossly outgearing the encounter. The two emperors will heal each other for vast amounts of health when they are near each other and thus soloing this was always thought to be difficult if not impossible.
Nowadays with all the Dragon Soul gear, the amount of DPS output will overcome their healing despite not being able to cleave/multidot, though it will still take a while to kill them.
There is a glitch however. Mind Flay did not seem to automatically refresh SW:P... so I manually refreshed it. Apart from that, everything else went pretty smooth.