i think he is a little overated considering all he does is a normal 2 foot blast with slower right hand a lot of the time. i've never heard him bass drum fast. the gabba bass drum sound he uses makes it sound more impressive - i dont like the sound, though it suits what they are doing.
to be fair, i've not seen any evidence of gravity blasts. on their last album it's clearly programmed / semi programmed / edited drums, as there's a blastbeat going on and cymbals being hit over the top constantly without any stop in the blastbeat. unless their drummer has 4 arms i don't see how anyone could believe it was real (then again that totally isn't the point of the berzerker so who cares really
)
from what i've seen i have my doubts that their drummer could break the world hand speed singles record, as none of their material is that fast consistently and his right hand seems weaker than his snare hand. that might explain why their "fastest drummer" claim was never authenticated? who knows..