A/B Split Testing and Optimization?

[McLovin]

Possible? Yes.
Practical, a good idea, easy to implement, etc... NO

What does GACE need to "test" these two different templates? If it is some sort of uri difference, then the question would be if the uri contained a parameter such as template=1 would that work for them?

In essence that is what the plugin should offer/allow. Designation of the template to be used through a uri get parameter:
Your host dot com/index.php?template=1 as a generic example would be for the one page, where as = 2 for the other. Otherwise, would suggest some sort of htaccess rewrite to append the template parameter based on the input uri which would also rewrite to the zc site appropriate address. It's really a lot about what does GACE require and what are standard setup methods for ZC that could support the expectation. But renaming/cloning/duplicating the index.php file is definitely something requiring a lot of additional work and relatively breaks the overall processing/operation.

I've added an example screenshot of how Google Analytics performs a content experiment. Basically you need 2 (or more) landing pages. One original page and one variant of the original page. GACE will then send half (or whatever percentage you've set) of your visitors to one page (the original) and the rest to the other page (the variant). Depending on your goals (for example minimizing bounce rate) GACE will then analyze which page performed the best (had the lowest bounce rate in this case) and - if you want - compare it to another variant to see which of those is the most successful page.

This is very easy when it comes to static HTML pages, but I'm starting to think that it might not be that easy with ZenCart. Which is really a shame, because you don't really need a fully functioning template, you only need two or more variants of a landing page that you can compare.