I hate to tell you 6fingers, but Rocktron only runs the signal through the tubes to warm up the sound a bit, the preamp is still digital. That said, Rocktron does make great stuff, I've used lots of their stuff since the old ProGap and Maxe preamps. The original ProGap is a great sounding preamp, it's digital controlled ss analog. But, is Rocktron the "only" company that makes good stuff, NO. My current setup is a Digitech RP1000, a Rivera Rake head, and an OD pedal or two in the stomp loop of the RP1000. I'm using the RP1000 because it has great amp models, but is also very easy to set up to work in the "4CM" with a real amp with the amp models off. They are the first to really implement this setup easily. (For you Boss guys, I know it can be done with the GT-6, 8, and 10s, I used to use a 6).
So, the original question was about the Zoom, I can't answer that one, don't know the current going price for them, but, if it gets the sounds you want and is a good deal, go for it.