A clone of channel three with the mid cut from the Herbert would be sick. The Herbert is my dream amp and if I could get close with the RM100 I would be set.
There's no Herbert around, but Anthony at Salvation mods does a fantastic VH4 mod. Check out his stuff on the 'Rigs and Tones' page, he does the best high gain mods around; thus far from Mesa, Framus, and EnGL.