Hi Jeff! I don't know very much about Adapted or Essentials or, the differences between them but, I can say for sure that, a newer version of Reason/Reason essentials should have no issues opening old 4,5,6 files.
Hope that helps
All the best!
EDIT: I may of been lying a bit....I'm not sure if R Essentials can open files from "full" version of Reason. Missing alot of devices...
Ok I guess I am of absolutely no help here! Sorry for that