I have not tried the 667, but have played the Thrasher, Satan and Diablo models a lot. They're all fantastic sounding amps. The Diablo having an impressive clean channel, and a very good sounding yet kind of plain distortions. The Thrasher having a very cool clean channel, and a distortion that seems very tight and dry yet at the same time has a lot of character and enough warmth to make it very satisfying. The Satan is probably the trickiest of them to dial in for a variety of tones, and seems geared towards the most brutal genres, yet seems to be rather flexible in producing 80's rock/metal tones. To me it feels a lot looser to my fingers and a sounds bit less hi-fi than the Thrasher; and for some reason I can't quite nail down, reminds me of the Kerry King JCM800. All great amps, so I don't think you should expect any less from the 667. Also, I've heard a lot of great things about that amp. Keep us posted because I'd be interested in reading a good review.