Hi I tested a Herbert, a Invader an Engl SE and an Engl Powerball all in the same Room and with the same Cabinet and the same Guitar.
In my oppinion Herbert was best, Invader second, Powerball third and Special Edition fourth.
You have some nice, well known sounds in the Invader. I would say for soloing, the Invader has better sounds, because they are very compressed and sound even. Herbert ist tougher to play - you hear every nuance, but also every little mistake. That's good for me - i like it
For rhythm, Herbert beats all the Engl sounds. No Engl can produce this power or this dynamics.
So i bought a Herbert for its open dynamics, power and clear sounding high-gain sounds. (I play mainly rhythm)
Invader: Full Mids, cutting through soloing sounds, relatively "warm sounding" high gain sounds, able to dial "classical" sounds, high gain sounds are comressed, fast responding amp, every channel has it's own character, big loss of sound on lower volume level, only metal amp.
Herbert: Full base and presence, more scooped sounds, relatively "cold and modern" sounding high gain sounds, able to dial "new" sounds, high gain sounds are open, faster responding amp, whole amp has a character, sounds still good on lower volume level, more versatile amp.
I hope this helps.
Greetings from Switzerland