John, agreed, Zurb is a great tool.
The only thing with Zurb is that they still require the Marketer to code the HTML. Zurb's templates do not have Marketo editable regions that will allow Marketers to be able to edit their templates inside of Marketo.
With Knak's templates, the marketer NEVER has to touch the HTML code. Not sure about everyone else out there, but the less I am in the code of an email, the better! I usually end up breaking something...
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