is there any changes or improvement when using EF-D or just the grid that's cool?
There are no changes nor improvement upon installing a EF-D but it's the same screen you have now but with a grid overlay. I use it on my 5D2 because I have the intentions of using it to help me not straighten out all my photos in post and it does help me align my landscapes a lot easier. It's not really needed if you straighten photos already in post in the normal workflow but I guess that's why it's also just a cheap mod to do to the camera. Not necessary but not a bad option to install either.