Sorry for the delay. About changing image file names, allowing it on orphaned images seems like a good compromise. But given the plugin is a power user tool, adding an override option would be a nice touch, so that one might use the feature on non-recommended ways if he so desired. IMHO, the best place for such an option would be a
define to be manually added to one's
wp-config.php. Having it as a simple check box would be dangerous. :-)
That reminds me: one thing I'd love to have would be the ability to have an image as an attachment to more than one parent post, so as to take advantage of the built-in gallery. I know this isn't how the database is structured, since in it an "attachment" post-type can only have a single parent. But I think it might work if the plugin allowed one to create a new attachment post pointing to an already existing file. It'd be something like this:
Parent post 1 -> Attachment post 1 -> A file
Parent post 2 -> Attachment post 2 -> The same file
Parent post 3 -> Attachment post 3 -> The same file again
Oh, and a small bug I found: if a title, alternate text and/or caption (I haven't tested the description) includes a single quote, it breaks the edit single item page. In the three fields, the string is cut at the single quote, anything beyond it disappearing. Additionally, in the caption field
<p> tags appear.
I hope this helps!