Understandable, but I've made highly customized versions of other community sites, and upgrades have always been a breeze. I've never had to set up separate databases, duplicate instances of the files, etc. (though I do, of course, back everything up before updates).
I like ZenCart, it has nice features, it's been great to customize (and I've created a highly stylized version of the store, thus many customizations) and I have no worries that I can handle the update myself..
The problem lies in the fact that I will be handing this off to the client upon completion, who will never be able to handle an update like this. Heck, in my experience, clients are even hesitant to press that "update now" link in the friggin' wordpress admin, which is about as hands-free as it gets. 
But, I digress....
So, you say there's only a handful of files between g and h the have been updated. Is this list in the release notes wrong? I want to make sure I'm not looking at the wrong changelogs.
PHP Code:
Changed Files (since release of v1.3.9g)
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