Thank you for your reply.
Regarding the sizing in mm, I know a fixed ratio can be handy sometimes. I was not trying to say that it should be removed. Adding a custom sizing would be very handy. Also, I know that in the main screen you can see the size of your carving/engraving in mm, but if you type the acreage (stupid unit) wrong, then you have to load the picture all over again, adjust settings accordingly again, and then guess if it will be right this time. I think it is a bit unhandy. I want to engrave my own pictures, not stock pictures. Another thing that could come in handy, is resizing your text/image in the main screen, like for example in word, with the arrows.
I own a 3D-printer which uses Repetier-Host as a slicing program. That program contains an emergency button, which comes in very handy sometimes. It works almost instantly. As adding endstops which for example the ManaSE board is not possible, I really think that an emergency button is a must!