Maybe DAZ will develop a sidegrade for Bryce user to get into Carrara. I was once a diehard Bryce user,  but wanted to build my own stuff. I gradually moved to Carrara 3 or 4 years ago. As of Carrara 5.1, with GeoControl and some plugins that are available or soon to be available,  I can tell you that Bryce can't touch Carrara's landscape capabilities. Volumetric clouds, surface replicator, plant & tree generator with wind animation for trees,  translucency, HDRI, indirect lighting, visible light cones that are interactive with translucency and transaprency, and great terrain distribution shaders are just some of the featues for that. Also, Hexagon 1 is a great modeler, and Hex 2 is going to be amazing with the displacement brushes, 3D painting, and UV unfolding. With both programs, they are almost unlimited in their 3D capabilities.