Hey Montius!
I've tried the Diezel Einstein head with the matching cab at the guitar shop here, and I must say, it IS a great sounding amp, but a bit fizzy for my taste, and certainly not warranting the $3000+ pricetag. The drive channel sounds too modern for me, altho I bet, as with any other amp, with some time and tweaking, I'm sure you can dial in a tone that suits your ears. I believe Billy Corgan uses Diezel, as does Billy Joe Armstrong from Green Day. I saw Rivers Cuomo's rig a few years back at a Weezer show and he was using Diezels, with the logo modified to "Weezer" with the same font.
My opinion is that it has more of that modern rock vibe to it. That's my take on it, hope it helps!