Though I have never used this, I believe from everything I have read on it, that it would be a major upgrade over TinyMCE and fckEditor. I believe the admin speed would also increase as the total weight of the editor is only 45kb. The features I would like to personally see implemented as a part of this:
Ability to customize what controls are presented when an editor is loaded. Example: most of the time, I don't want me clients to have the ability to change font color, change font sizes, adjust justification, etc. I want them to have RTE for bold, italic, adding images, links, and adjust between headers/paragraphs/blockquotes. I believe adding this, with setting up site-wide settings and allowing overrides (for app RTE attributes, page content layouts, etc.).
This would also allow click-to-edit ability: http://imperavi.com/redactor/examples/click-to-edit/ or even the air mode: http://imperavi.com/redactor/examples/air/http://imperavi.com/redactor/examples/click-to-edit/http://imperavi.com/redactor/examples/air/
It also has built in auto save functionality and supports HTML5.
Finally, this works iOS and Android 4 so editing the site on tablets and phones would be possible.
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