Ophidian Aspect helped with reloading everything faster, since rockets were the primary source of boss dps, I wanted to keep those loading faster. Stormcaller was a lot more consistent and simplified things. I'm sure there's some sort of Voidwalker strat out there, but that would just take an unnecessary amount of planning. The fact you can get full super points from a full wave of enemies in a shorter amount of time is what sold me to Stormcaller.