The new graduated flood fill routine is very useful and I've just started exploring it's possibilities so I can provide some guide for it's use when we release but there is much to explore as it allows map makers the ability to do things they could never do before
BUT... there are some things you SHOULD NOT do
You
REALLY( really,really.....) want to avoid over mixing contrasting terrains
.unless you are doing a study on the effects of camouflage because there ARE hills in that example..good luck finding them
"Subtle" is what you need to aim for...if you put hills, trees, building and roads on this example it will blend harmoniously without a monotonous single type of grass