Tandems and kid friendly kayaks

Saw this oasis on CL today.  Older model (~08), but with sail kit that's a hell of a deal.  If my son were a few years older and I had more storage space, I'd probably be all over it.

http://seattle.craigslist.org/kit/boa/3905322086.html

So, how's the OK Zest as a comparison to the Malibu 2XL?  I'm seeing a lot more Zests on Craigslist right now.  Seems like it would be a bit faster, possibly less stable (but probably not to a degree that would matter), but not as set up for fishing out of the box.  Anyone paddled both?