Upgrading from 2.1.x to 3.1.x

Thank you for the replies, I am thinking now that I just need to spend more time working through these bugs I am having with HMVC. I was able to get a brand new CI implementing HMVC but after migrating an existing demo site that I have, I run into an error with HMVC that I can't trace down. It doesn't make sense because it uses the same HMVC code as the working skeleton site that I have working.

Fatal error: Call to undefined method CI_Router::fetch_module() in /Users/corby/Desktop/Sites/project/application/third_party/MX/Config.php on line 42

@orionstar I have not run into that error yet but thank you for the link...how do you load your spark libraries? I currently have them setup in a MY_Controller file loading as such:

$this->load->spark('template/1.9.0');
$this->load->spark('message/1.2.1');
$this->load->spark('cache/2.0.0');