Concrete5 has the block model for sure, but I believe the editor is standard TinyMCE. Sir Trevor seems to take this to the next level, with the ability to configure a block for context specific editing. This would be a nice enhancement to Concrete5, or perhaps a new add-on.
One improvement to Sir Tevor would be to provide drag-and-drop ordering, which Concrete5 has today.
It has it, it's just not as slick as it could be. In Sir Tev, you're moving a copy of the object, whereas moving the actual object would be cleaner, and more obvious. At the moment it looks more like when you accidentally grab an image and move it (for it to then snap back into place) in some browsers.
One improvement to Sir Tevor would be to provide drag-and-drop ordering, which Concrete5 has today.