I'm here to highly discourage you from trying out the features that the Spintiremod tool offers in the editor. There is a high chance, that you will screw up any existing map-- especially the lighting.
I decided to try out all of the height features, as well as the extended map stuff.
Afterword on all of my normally created maps it had streched them to the extended size, and the extended heightmap. Making the map useless. It will also change the way the tools work as well.
The options sound great, but if you have much work on anything map wise , I hope you don't decide to screw up your editor.
It was a challenge to get eveything back working normally again.