I'm pretty blown away with the Hagen, and that's coming from a guy who was hooked on the VH4(S) for several years, and also messed around with a Herbert for a lengthy period of time. The Hagen is a simple amp, but its 4 channels deliver incredible sonic oomph and signature Diezel tone. I love it.
Herbert hands down. It's all in the mid cut. The effect that one feature has on cleaning up the sound and delivering a tight, clean, metal tone when compared to having the mid cut off is impressive. The Hagen and VH4 do not have this feature..... case closed on what amp to get.
Hats off to you Peter with that design. I've played VHTs for years with the 6 band and a guy can waste a lot of time dialing in that band. The mid cut on the Herbert is so simple, fast easy adjustment, and just as effective.