Very very interesting efforts....and looking really sweet!.
As for the terrain tool of choice?...hey!,it's not about the price tag,it's the artistic ability to create a terrain even with MED;then a good texture work will do the rest....that's basically it. Sometimes we go through these portals of spending $$$$$,buy this tool; buy that tool.99.99999999999999999999999999%
of time we realized later,or after the fact,Oh man!......my point exactly?;use whatever terrain tool you want,start with MED it's free. I wish you guys the best in the final release.