I spent time with the two channel model that is now called the Viper and it will compete with the likes of Diezel, VHT, Mesa, Etc... Channel one is voiced to be the lead channel (i.e. more liquid mids and upper mids), channel two is the scooped sounding channel for heavy rythm thumping if you want it. it uses 6550's in the power section and is very defined. No mush in this amp. It also has a lot of harmonic richness. If you can do it, A/B this amp with the others mentioned and strum an open E or A chord and listen to the richness of the sound. Andy Fuchs has done an excellent job for the high gain community. My dream set up would be: Fuchs Viper, Fuchs TDS, and Fuchs Train 45. With these three amps, you can cover it all.
The Viper (which replaced the two channel Frost) is currently on tour with Korn. Shane Gibson, the new lead guitarist for Korn is using it. They are filtering out there slowly but surely. It's nice to be recognized by a new market segment for doing something different from what we'd done before.
The Viper has a "Thrust" control (like Peavey's resonance), which adds low end to the power amp. It has a cosmetic facelift over the Frost graphics (which I never much cared-for). A few other minor circuit tweaks (mostly production upgrades we were doing "on the fly" to the Frost anyway). The amp was renamed as our agreement with it's namesake was terminated.
Ralphie had a loaner for a few months to record some soundfiles.