Two days ago - after long consideration - I finally took the plunge and bought a 50W Artist Edition.
The amp sounds really, really great, and it definitely doesn't lack thump. Its low end is more percussive, less compressed than other Engl amps I have tried before (e.g. Fireball, Invader) and it has LOADS of gain (with a boost in front the lead/gain channel sounds nothing less than apocalyptic with the gain above 10 o'clock).
I would describe the overall voicing as a mix between the polished, slightly scooped Engl sound and a more aggressive modded Marshall. When dialing in a tight Thrash tone I found that treble and presence settings above 5 1/2 can get a little bit spiky (although that could also partly be my Suhr Reactive Load's fault, which is known for emphasizing the high end) and I raise the mids to 6 1/2 to fill out that Engl scoop a little bit. Adding mids with the shape switch is a little bit too much for heavy rhythm guitar, but it's really useful for leads.
Another thing I found is that the amp is remarkably quiet, even with a lot of gain. In fact it is even more quiet than my amp sim plugins through a high quality DI box. I leave the internal noise gate off, because it cuts off the sound really hard. I prefer noise reduction with a more adaptive and dynamic response (e.g. ISP Decimator), but to be honest I don't know if I even need it for this amp.