I just cleared a GR45 rift solo in 3 minutes 24 seconds. I know there's plenty faster out there (I'm pretty sure i've done faster myself with a chicken), but yeah, speed isn't exactly this build's problem - I don't really have any great gear rolls or augments or what-have-you. And I'm still getting the hang of this build.
I also just realized why my damage seemed to be down - I replaced my Fury of the Vanished Peak (Seismic Slam half price and 5x damage) with the IK hammer (necessary set piece). I might have to throw the other one in the Cube
It's fun, and it's a very different gameplay loop than what I'm used to from necro/WD/Wiz, so, hey.