A great post. I have been a fan of the Killing fields terrain matts for quite a while.
I plan to use three of them for my game at Historicon.
I really like what you did both in shaving some of the fur down to reveal different colors and in using the paint to get different colors. I plan to give it a go on my mats, unfortunately there will not be time before Historicon. But I should have more time over the winter.
A few things that I have tried using these matts:
1) I shave down the matts completely to make roads and then make a mixture of brown paint, model railroad ballast (for texture) and about 50% Elmers glue (keeps them flexible. I then add water as required and just paint it on to make the roads. When dry, I dry brush with a lighter color for highlights. I find it works well.
2) I was making some field defenses/hills using 1" foam boards. I was wondering how to decorate them to make them blend in with the killing fields mats. After several months messing around I tried covering the hills with off cuts of the mats and leaving the mat to overhang the edges by about 1". They seem to belnd in surprisingly well with the underlying mat. Here is a photo, which also shows the road.
3) In your blog you discuss that you want to do a marsh. I actually use the Killing fields static grass mats for marsh and overlay the fur mat on the edge. It gives a great marsh look. I am still working on this technique but it is showing promise.
Keep posting your ideas, it is great to see what others are doing