Thanks Shadownox (been away on hols for a couple of weeks hence the slow response).

All comments appreciated so I'll certainly have a play with some darker brown on the flat land and see what it turns out like.. and yeah I'm not sure about the borders either. I want them to be visible, but without standing out or covering the regular map detail if you get me? - so anyway I'll try for some sort of muted colour and see how I go.. I'll post an update soonish