Ninja MultiContent is really a clever addition to the Ninja Forge Extension Treasure Trove.
My findings so far:
-install went smooth on my Joomla! 1.5.20, no errors.
-great and user friendly design.
-overrides per article - perfect.
-general use is working as it should - perfect.
-easy 'out of the box' use - perfect.
-I see a great potential for this component for public use.
-add history of recent added content.
-possibility to edit (multiple) content listed in history.
-possibilty to choose also Sections (I guess you didn't add this because of the fact J! 1.6 doesn't make use of sections in the future).
-Ninja MultiContent Joomla 1.6 ready. Allthough I'm pretty sure this is your intension too of course, just mentioning (I'm aware Ninja MultiContent is in Alpha). Out of curiosity I tried to install it on 1.6 beta 14. Didn't install correctly.
-multilingual - I volunteer for translating the Dutch part, if you like ;).
-possibility to preview content.
I'm testing it some more and will give my feedback if there's more to report.
All and all...Great Job!! so far, Richie.
Keep it up!! ;).