I've had a screamer head for about 3 years now. The last 1-2 years I hardly touched it as I was into modelers and my low-powered THD amp.
But recently I started playing in a band, and after some approach to go with the THD and programs in the Tonelab, I decided I needed some more pure sound approach with more channels and tried the Engl again.
As mentioned before, I can get 4 distinctive, usable sounds from it, from their character I would describe them as 1: Twin; 2: Bassman/Plexi; 3: JCM800; 4: Recto (not saying that all 4 would be as good as the real amps).
Common EQ is limiting, but no disaster to live with - I have to say, a second EQ would be nice though. I agree that with all its features and rear connections/possibilities, it's a fantastic bargain. With the Z5 footswitch (you HAVE to have it) it's around 1200 EUR new, which is 300 EUR per channel :)
The only thing I'm still feeling is a lack of character in the tone. I mean it's rounded, got ooomph, cuts through, string separation, pinch harmonics, sustain, etc - all very very good. BUT if I plug into the THD or even the small Epi Junior, they feel more like instruments to me, whereas the screamer is ... well.. an amplifier. This is probably very subjective and might just be related to those amps having a fuller, warmer tone. But to me, although I love to play the Engl for all its qualities, I don't feel 100% at home with it.
So at least I have a reason to still look around and GAS for a Soldano, Bogner, Matamp or Cornell :)