I could not say I like one over the other because they are different enough to be utilized for
different needs.
The Herbert has a bell like clarity and and the percussive response of a grand piano. The tone, I think is unique to only the Herbert. The VH4 has the ability
to alter the cleans with the gain knob and bright switch like Olaf said. It can go from funky compressed chicken' tones
to dark overtones all the way to breakup ala pushed old Fenders. For blues with a clean boost the VH4 Ch. 1 is very
good, the Herbert not so much but the 2 - is in a world of it's own for boosting. The gain knob interacts so well with clean boosts
and the tonal variety with the mild compression with increased gain makes it sing it's own song.
I really don't feel anyone here is going to help you with your question. You need to go and find out in person.
It's difficult to try and sway someone from one Diezel to another when you already have multiple models.
They are the most addictive drug to tone junkies.
Here is a great vid of Rob Tahan and some Herbie blues.
https://www.youtube.com/watch?v=jSsMdkbDdE0