Hi Ed, there are a number of improvements in the coming KS5. The ability to create sun/sky HDRi environments directly in the map editor (pro version). In fact most of the enhancements are in the pro version. Motion blur has been added to the basic render engine so you can get more realistic results from animated objects. Instances will be in there. Another beta tester has just today pushed KS5 to render a scene with over 2.1 billion triangles on a 24gb 8 core pc !. There are some massive speed enhancements, material editing improvements. It's a big step forward this time. The areas where KS4 and KS3 were considered weak have been addressed in this release, still not perfect (if there is such a thing), but it's a real good start.

If you are the same Ed from the KS forum, you have been offered a chance to beta test KS5 too

Martin Spencer-Ford