Is there any chance you can add css classes to the meta boxes on the add testimonial page when you next update this plugin please?
That way we can hide certain meta boxes on the back-end.
For example, the GROUPS part of your plugin isn't needed in my case so it'd be nice to hide that from my client, so as to avoid any confusion.
Same goes for the website and date fields...
Without css classes added to each of the meta boxes, we can't hide them individually