Interesting... and sounds incredible.
I have a Tech 21 Liverpool, which I love (playing a strat through it into an Ampeg Jet 12R right now, actually) and a Seymour Duncan Twin Tube Classic that I've yet to really put through the paces. The Ethos takes it to another level.
I've heard amazing things about these:
http://www.siegmundguitars.com/pedal.html like the Duncan Twin Tube it uses military grade micro tubes like a power amp inside to get the tone.
These things all do make an okay amp sound like a stellar amp.
Considering what I spent on a Hotcake, a great Lizard Leg transparent clean boost and the Liverpool together the price for the Ethos is not as high as some will think considering all it does.
The "eventual purchase" list just got longer (and rearranged).