Default import profile allows to upload configurable products, but in my case (I have lots of associated products) it's really a nightmare. It's better to use the <a href="http://mag-manager.com/free-download" title="Store Manager for Magento">import</a> tools that optimize configurable product creation, especially if you have multiple configurable attributes. By the way Magento 1.9.3, as I have heard from community users, has changed some logics