I do a lot of prototyping on the command line with drush. This allowed me to test switching content types. It's very bare bones but it's a good place to start.

gistfile1.txt

drush ev '
$query = new EntityFieldQuery;
print_r($query);
$result = $query->entityCondition("entity_type", "node")
  ->propertyCondition("type", "morning_message")
  ->execute();
print_r($result);
foreach ($result['node'] as $row) {
  print_r($row);
  $node = node_load($row->nid);
  print_r($node);
  $node->type = "news";
  node_save($node); 
}
'