remark: an alternative way to mass edit is via phpmyadmin

PhpMyadmin has enough features: filter/select rows and mass edit on one page.

The caveat: it is backend editing so if you update a field that runs some drupal hooks/functions/(updates another field or variable in the site) - you won't get them updated via phpmyadmin editing ...

For the node titles and lots of things this is ok.

For the body and teaser I am not sure... Maybe a massive "Save post" via Views Bulk Operations would do the job of syncing teaser with body ... (This has the slight drawback of updating the modified date so if you rely on it for display/ordering you may spoil your list orderings...)