IMHO the biggest challenge would be textures themselves - DT won't accept a map with textures made from copyrighted satellite images, which most mod maps use.
Also, any water-logged type of terrain, like marshes or rice paddies, is hard to reproduce. I mean something like this:
http://www.nicolastrudgian.com/uploa...ections/40.jpg
Such textures won't reflect water, hence they will never look 'right'.
By the way, the latest HSFX 7.0 is based on 4.12.