I used the bulk editing feature of Post Type Switcher a year or so ago when I was doing some site restructuring adding custom post types. I coupled it with the Taxonomy Converter plugin to handle custom taxonomies for the new CPTs. In one case I was going from page to CPT, so used the approach covered here, http://www.markwarddesign.com/2014/02/remove-custom-post-type-slug-permalink/ (the original WP VIP link no longer works), to keep the URLs the same.

It's definitely a valuable, temporary niche plugin. And, as you mention, these types of changes are definitely best tested on a staging site before going live!