I'll answer both questions posed above:
1. As for cabinet and speakers matched to the V series of Diezel amps, I think it is VERY safe to say, several have tried to wander outside all that is Diezel in their pursuit for something different. In the end, every individual who went with the Front Loaded 4x12 with G12K100's was 100% absolutely torn to shreds and blown away. I am one of those people, and I KNOW Pauly will chime in here as well... And probably everyone else. They are torrid sounding cabinets with potency that is out-of-this-world. Just do it. And NO, I do not work for Diezel
2. Having an Uberschall steered me away from buying a Herbert due to the fact that I found the Uberschall TJ offered a looser, easier playability, ultra high gain tone with tremendous low end and lots of dynamics. Having already in my possession the VH4S, which is, as I've said before - surgically tight and immensely powerful and super articulate, my Diezel tone was satisfied right there. The Uberschall TJ is a player's amp, there's some flex to it, and it offers a lot of what the Herbert does (in this application of hi-gain, thrash, metal-drome voicings). The Herbert also offers a lot of other great stuff - but I get a lot of that other great stuff with my V. So, rather than overlap "great stuff" with two amps, I went with one VH4S and one Twin Jet Uberschall, and between the 2 of them, I get anything I want. To me, personally, if I owned 1 Uberschall and 1 Herbert, I would, in essence, only own 1.5 amps - if that makes any sense.
Peace,V.