Let's export Shopify to OpenCart. OpenCart is designed in a way that all of its pages can be indexed and identified in search engines. So by providing the identification information through Meta Title, Meta Description and Meta keywords, you are making it easier for search engines to get your store data. OpenCart allows the use of search engine optimized URLs for product, category, manufacturer and information pages. SEO keywords are defined per product, category, manufacturer and information page, stored in a database table (url_alias), looked up at each page request, and translated into an internal URL. Here is some SEO tips for optimize OpenCart site: https://www.linkedin.com/pulse/11-seo-tips-boost-your-opencart-online-store-sourabh-nagori

I will share about my case and how my business do.

1. We have two site that is http://litextension.com/ and http://blog.litextension.com/

In each site, we set up many paths to other site. We create site blog after main site a long time. However, we focus on content on site blog, almost indexes of http://blog.litextension.com/ are higher than http://litextension.com/ . Then, we add a lot of dofollow link on site blog, which leads to the main site. They are support together.

2. We creates many satellite sites to drive traffic to main site and blog site. Of course, we use social media site maximum.

I suggest WooCommerce, which is a free WordPress plugin and one of the fastest growing shopping carts. Many small business used WooCommerce for their online store. They recognized that it allows them manage site with simplicity and SEO friendly. It is difficult to say that WooCommerce is the best SEO friendly CMS platform. However, I think it is a good solution for small business because of cheap cost and effectiveness.

If you are sure about WooCommerce and WordPress, you should try WooCommerce migration tool by Litextension to convert to new site with keeping SEO URLs. Check it: http://litextension.com/woocommerce-migration-tools.html