Ah, sorry I've already come pretty far in writing my own editor. It supports the 9 cells per tile with full zoom, pan, variable materials/terrain. I just need to add the UI elements for add/remove material and the XML persistence code, and it will cover the same immediate needs I had of Tiled, with the benefit of being very easy for me to evolve alongside my game. It also gives me the opportunity to throw in game-specific metadata and other features, which will be important for procedural generation. Really, I should have gone this way from the start.
I appreciate the response, and I think it is great you are providing a tool like this for people who, perhaps, cannot make one or would prefer not to spend the time doing so. And out of those I demo'd, yours was--by far--the most polished and pleasing. Cheers!