Content that adds value to the user experience is never bad - more content, more reasons to rank, better information for the user to take action.
Ecommerce websites are more difficult to handle though - the goal is usually to convert to a sale and sometimes content can get in the way of that happening. If you've A/B tested and found that conversions are greater without it, then good for you! You've identified a barrier to your visitors and eliminated it for better conversions.
What needs to be weighed is the amount of conversions - does the content bring in more, new traffic and eventually converts? I.e. is the conversion volume greater with the content than without it. If no, then stick with the A/B test results.
Putting content down the page may help you rank, but is it helping your visitors? You don't want to shove content onto a page just because you think it belongs there - is it beneficial to the user? If no, can you put that content somewhere else where it is beneficial to the user?
Amazon is common SERP to beat, let's take a look at one of their category pages: http://www.amazon.com/Outlet/b/ref=sv_gb_3?ie=UTF8&node=517808
We see that they do include a small snippet of text at the top, to describe the category. Then they give the user what is expected, a lot of products to view; and at the bottom they have a longer category description (sometimes reviews and related category information). This is a common way to structure category pages. But, your market may be different so it may be worthwhile to brainstorm how your page structure would most benefit your users.