I've never actually sat down and played with the digiverb...mainly because I'm not a real big fan of Digitech products in the first place

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I own the Verbzilla though, and it really is a fantastic little pedal. I'd say its worthy of the praise it receives on here. It also has stereo ins/outs...
If you're happy with the digiverb, there might not be a whole lotta point in upgrading. But, if ya think there's something missing, it might be worth a shot.