Hi Peter
I think you overlook the implications of this paper. Genetically there has not been a loss- only a very slight change. The process is believed to have originally occurred from multilegged ancestor to six legged progeny, but could occur in the other direction via an equally simple genetic modification. The gain or loss of structures is arbitrary because the genetic change is simple and therefore quite possible in either direction.
This result doesnt directly demonstrate large scale evolution on a genetic level, but shows how simple genetic changes can cause large changes in morphology, reducing the necessity of transitional forms to evolution.
Shane