Okay, enough Diezel bashing. An amp is worth what you're willing to pay for it. I've owned Engl, and I can tell you that they are not the same amp. If I had to choose between Diezel and Engl, the Diesel would win, hands down.
If you want to hear a really good VH-4 tone, check out late Dokken, during Lynch's brief return. (The Live in '95 DVD for example) Since my guitar is the same as his, and my gain structure is similar, I can tell you that getting that tone is well within reach with this amp.
The VH-4 is incredibly versatile and has really good resolution and projection, tons of gain, and the most complex footswitch outside of a Bradshaw rig.
Build quality is ultra-high, too.
If you like a modern recto'd tone, but with a bit more mids and versatility, then this is a great amp for you.
For my style, I prefer the Roccaforte hi gain heads. The VH-4 is definitely worth tracking down, tho.