So here's the complicated scenario I'm dealing with:
A friend of mine and I share a server together that's got quite a few mods. There's more we want to introduce, but we don't want to put them all in the same world -- we want to make a separate one specifically for those mods (like one world for just average vanilla style, and another for all our magic mods). We currently use Forge and that's been extremely resourceful for us so far, but now we're at a hard spot, because it seems most of the multiworld mods out there depend on Spigot/Bukkit/Sponge/some other mod support. And I'm really not all that interested in switching to those, because it's tedious.
I do have MystCraft downloaded, and it says it delves into multiple dimensions, but I'm not sure if it can separate mods between worlds (or, really, how it works at all, thus I haven't uploaded it to the server just yet). SimpleDimensions looks alright but I've noticed that it seems lacking in terms of commands and GUI (though that could just be my opinion).
If anyone has any other method, that'd be swell.
Our server is supported by a third party, and while it has quite a few mods already, it doesn't get much traffic, as you might have guessed, so I'm not worried about having multiple dimensions causing lag or serious RAM usage.