First of all, I'm really sorry for my broken English :S
Split posts in pages with pagenames, since WordPress is able to do it, we don't need any plugin for:
<!--nextpage:Overview--> <!--nextpage:Specifications--> <!--nextpage:pagenameN-->
I mean, I know wp link pages(); but this is not for a generic navigation names (as post/partX or post/X/), this is for a custom navigation names. The url (or slug) doesn't matter for now.
What do you think about this?