Those are certainly kindred projects. Infinithree is still being defined, but here are some of my thoughts on how ∞³ should or must be different.
Deletionpedia was only ever a ‘morgue’ for deleted articles – with no option to start new material or improve old. That gave it an interesting ‘information rescue’ mission, but never the goal or potential for being a lively, independent site on its own. Similarly, being based on MediaWiki, and defined (in its very name) as a reaction to Wikipedia, limited its potential for exploring expansive new reference models. And now, Deletionpedia seems to have gone inactive for a couple years – and is no longer rescuing deleted articles.
Everything² is a bit closer to what I hope for from Infinithree – a broad conception of acceptable topics, and an identity independent of Wikipedia. (Indeed, Everything²’s roots predate Wikipedia.) But, Everything2 has no ambitions of speaking authoritatively, canonically, and in a shared voice about reference topics. Contributions are individually signed and are not collaboratively wiki-edited. Also, they’re not automatically under a no-muss no-fuss free content license, to promote the broadest possible use.
So neither of these projects aspired to be an expansive postencyclopedic reference work. Infinithree has that aspiration.