I don't really have a special single player world so probably just start new.
On the SMP server I run, MCEdit doesn't make sense; there's a lot of underground and interconnected things that rely on the surrounding terrain. I'll probably just delete the unbuilt chunks around the edges and let them regenerate like usual when there's an update to the world generator. This time will probably need some experimentation to try and get things to blend as well as possible, though.
Rollback Post to RevisionRollBack
My Spigot/CraftBukkit plugins: TallNether - Generate a 256-block high nether
User: *BOOM* You're dead.
Cleverbot: I divide by zero and come back as an angel ninja.
I guess I am lucky in that I only really started playing a week or two back, so I don't have anything interesting on any of my worlds.
So yeah, I'll probably delete all the current ones too, except my redstone-test world, which won't really be affected as I just mess with it in MCEdit anyway.
-shrug- I've just not gotten attached to anything yet.