Some possible design changes are in the work, which touch upon map building specifically.
Instead of going with a more free form painting and placement style system, we're looking at instead simply making various template style pieces that snap together. Similar to say the spacehulk board game, yet being city based. This should allow for super easy layout of maps, while also allowing us to enforce certain aspects to make sure the game feel and any technical limits are always addressed regardless of map design.
Also this likely allows us play with some other interesting aspects like the pieces being very much just layout based, and the game procedurally placing graphics as needed upon map load. In this fashion, every time you went to play a given map, it would have the same layout, but the roads, building types, and other bits of decor would be randomly chosen. This means we could also patch in new graphics for additional variety and maps would automatically be able to take advantage of them.
The possibility of an actual full fledged random map generator opens up as well with this change.
At any rate this change probably also means less time spent on map editor development and more game development happening. Still its early days for the project, and nothing is set in stone yet. (Well other than awesome mechs, multiplayer, action points and some other stuff.) :)