Confirm that the HTML5 plugin (extension) SDK matches the C/C++ SDK plugin feature set in every way

Im looking to develop an HTML5 plugin for Premier.  I want to create something similar to http://www.pond5.com/adobe.  I realise this plugin is fairly complex - will I be able to create such a complex plugin using HTML5?  I realise that there is a C/C++ way of developing plugins, so Im just concerned that the HTML5 method might not support the methods I will need for my app - things like drag n drop audio clips from the plugin window into premier.  Can any developer please confirm that the HTML5 SDK matches the C/C++ SDK features in every way?  Thanks in advance, Ross