I'd say, currently, nobody is "right" on this... The Visual Dictionary is as much a piece of EU as anything... So is the "Official Site's Databank", Comic Books, or pretty much anything else...
I think everyone, despite what's in print form anywhere, should judge by the film only as to what's "fact" or not. The Databank puts AT-AT heights at 15m when the film shows they're clearly a bit larger... If we're discussing "canon vs. non-canon", then the films will forever be the only true evidence, and so far nobody's got that backing them up.