Great post about the Goodl and Bad associated with each ecommerce platofrm. Very detailed and accurate. I've used Shopify and Magento. I found Magento to be powerful but SLOW. We create Magento ecommerce websites at Atlantic BT and they must be served correclty or they too are slow. 

Shopify clearly benefits Shopify, but wrestling benefit out fo their platform for yourself is a differnet challenge entirely.