How to return a view to an ajax call ?

Hi,

I recently had to modify some code of my colleague. I saw that we don't handle ajax calls the same way.
When it's about returning data, we both use.
   

Code:

echo json_encode($this->upload->data());

However, when we have to return a whole view, we are a bit different :

He uses :

Code:

echo $this->load->view('theview',$data);

I use :

Code:

$view = $this->load->view('theview',$data, TRUE);
echo $view;

I also saw somewhere online

Code:

$data = $this->load->view('theview',$data, TRUE);
$this->output->set_output($data);

Those techniques seem to work correctly, but what the best pratices say about that ? Is one of them safer, faster or more "MVC friendly" ?

Thanks