[eluser]BrianDHall[/eluser]
You should use the latter form, for many reasons, but most specifically and simply the latter method allows you to have more than one Foo - and you'll often find you need such functionality when you least expect it.
Code:
$user = new User();
$user->get_where('username', 'shuckyducky');
$user->sig_line = 'Shucky!';
$user->save();
if ($command == 'delete')
{
$user->delete();
}
Also it is a lot less code to right to avoid use of $this->User - you could just have $user or even just $u.