[eluser]Zorancho[/eluser]
Yes you can use $CI = & get_instance() in a helper, especially if you need to use some of the core libraries.
Code:
function do_something_or_else()
{
$CI = & get_instance();
$user_id = $CI->session->userdata('user_id');
}
I use helpers for logic in views mostly, but sometimes helpers like URL is very helpful in controller especially the base_url() method or if you are printing HTML in a Controller AJAX method.