I say the more the merrier, you know? Why should the site be pigeon holed to one single thing or one engine. Like you said, if it has an editor then maybe you should try and include it. Everyone can benefit from some sound advice sometimes even if they are different engines. Level editing is pretty much the same no matter how you cut it; even the 2D stuff.
Don't laugh, RPG Maker is the bomb! Gotta love the Japanese!
I would love for the new site to have some sort of resource area. I know we push for originality but it wouldn't hurt. I know everyone is against prefabs too but they give a great base for someone to at least learn how to make complex brushwork. Just an area for some basic resources and links.
Maybe the resources could be cross platformed so they could be used by all. Like leaving texture images to their original source instead of rendering it to a specific engine. That way you still have to work for it.
And definitely more tutorials for all engines included.