I like the idea of the thread, but respectfully disagree with this statement.
The Zone's one of those discs that's hard to be "on the fence" about. Either you like 'em or you don't. They're a relatively popular mold, and a good segment of the crowd likes them, but many of us simply don't like that much overstability in a putter. It's really all about preference, but I wouldn't say it is "underrated" - it gets a lot of praise from the not insignificant # of players who throw them, but it's simply not a disc for the masses.
That being said, Almost any unpopular mold could be considered underrated by someone who regularly throws and likes it. In their eyes, they can't understand why that mold isn't as popular as a Valk, or a Wizard.
Don't think of it as a putter. I don't know anyone that actually putts with them unless into a big headwind. Think of it as an overstable mid or approach disc since that is pretty much what everyone uses them as.